After sitting out the past four months with a right knee injury, a healthy Juan Martin del Potro returns next week as the top seed at the Delray Beach Open.

The Argentine, a wild card entry, kicks off his fifth appearance at this event with a first-round clash against Yoshihito Nishioka of Japan. The 2011 champion has reached at least the semi-finals in three of his previous four appearances.

Second seed John Isner, another wild card, starts his week against Canadian Peter Polansky. The American holds a 10-6 record in Delray Beach. Third seed and Australian Open quarterfinalist Frances Tiafoe faces a qualifier in the opening round, while fourth seed Steve Johnson begins his campaign with an all-American clash against Bradley Klahn.

Other notable names in the draw include 2015 champion Ivo Karlovic of Croatia, Nick Kyrgios of Australia and last month’s ASB Classic champion Tennys Sandgren of the United States.

View the full draw 

Twelve months ago, Sam Querrey was a tie-break away from winning the New York Open (l. to Anderson). The American might get another shot at the ATP 250 title this weekend.

Querrey advanced to his first tour-level semi-final since last year in New York on Friday, beating Jason Jung of Chinese Taipei 6-3, 3-6, 6-3. Jung had upset second-seeded American Frances Tiafoe on Thursday night. But the 6’6” Querrey hit 23 aces and didn’t face a break point in the decider to advance.

“I came out strong and ready to go in the third set and got the early break and that allowed me to free up. I got some momentum on my serve, allowing me to go for it on my return games,” said Querrey, who often practises with Jung in Los Angeles. “He had a great tournament. He’s a guy who makes you beat him.”

Querrey was close to cracking the Top 10 of the ATP Rankings when he fell to Kevin Anderson in last year’s final. From there, however, the American didn’t reach another semi-final and fell to as low as No. 59.

But the 31-year-old has recommitted himself to playing aggressively this year, and so far it’s working. In the semi-finals, he will meet Canadian Brayden Schnur, who’s having the best week of his career.

The 23-year-old Schnur was the final alternate accepted into the qualifying draw. Then he won two matches to make the main draw, but a semi-final run hardly seemed likely. Schnur had been 0-5 in tour-level matches before this week.

But he beat compatriot Jack Mingjie Lin and Steve Johnson of the U.S. for his first tour-level wins, and his dream run continued on Friday with a 6-7(7), 7-6(5), 7-5 win against Paolo Lorenzi of Italy. Schnur lost four consecutive set points from 6/2 in the tie-break, but he recovered in the second and scored the first break of the match at 5-5 in the deciding set.

“It’s definitely something I didn’t expect,” Schnur said. “I’m talking to my buddies, and they’re saying, ‘Your breakthrough week is going to come when you least expect it.’ Sure enough this week, I show up here, I’m pretty tired, came off having the flu, and now I’m in the semi-finals.”

In the bottom half, American Reilly Opelka reached his first tour-level semi-final in nearly three years, beating Guillermo Garcia-Lopez 6-3, 6-4. Opelka saved the only break point he faced and converted four of his six opportunities against the Spaniard.

The 6’11” Opelka awaits the winner of top seed John Isner vs. Aussie Jordan Thompson. Opelka beat Isner earlier this year at the Australian Open, but Isner beat Opelka the last time they met in a semi-final, at the 2016 BB&T Atlanta Open.

Stan Wawrinka overcame a second-set comeback on Friday to beat 10th-seeded #NextGenATP Canadian Denis Shapovalov 6-4, 7-6(4) for a place in the ABN AMRO World Tennis Tournament semi-finals.

Wawrinka, the 2015 Rotterdam champion (d. Berdych), awaits the winner of top-seeded Japanese Kei Nishikori, winner of the Brisbane International title (d. Medvedev) last month, or Marton Fucsovics of Hungary. The Swiss leads Nishikori 5-4 in their FedEx ATP Head2Head series and leads Fucsovics 2-1 overall.

“Physically I feel really good, and I’m moving and feeling better match after match,” Wawrinka said. “Tonight was a tough match. I had to really fight at the end. I was a bit nervous at the end of the match. We had some long rallies. It’s good to see that I can keep being there, mentally, physically.”

Shapovalov recovered from 15/40 in his second service game, but Wawrinka finally gained the break with a trademark backhand winner to take a 5-4 advantage. Shapovalov struck a backhand into the net to end the 31-minute first set.

Two double faults from Shapovalov handed Wawrinka the first game of the second set and at 1-3 another double fault — one of seven in the match — put the Canadian on the back foot. But a clever drop shot in the sixth game signalled a resurgence and terrific power off the ground at 4-5 resulted in a second break of serve. Shapovalov withstood the pressure once more to recover from 15/40 at 5-5. But Wawrinka pulled away in the tie-break and celebrated the win with a boastful “Allez!”

Bang. Bang. Ace. The pressure cooker moment of saving break points is when John Isner blows the ball right by you like no other.

An Infosys ATP Beyond The Numbers analysis of Isner serving at break point from 2015 through the 2018 season uncovers that one out of every three break points he saves (33.6%) when serving is an ace, putting him in a league of his own in this specific moment in a match.

For context, the rest of the current Top 20 average an ace 8.6 per cent (1166/13511) of the time they save a break point. Impressively, Isner is almost at four times that average, at 33.6 per cent.

The leading five players out of the current Top 20 who average the most amount of aces saving break points:
John Isner = 33.6% (187/557)
Kevin Anderson = 21.2% (154/725)
Marin Cilic = 18.8% (148/789)
Milos Raonic = 16.1% (87/541)
Roger Federer = 14.5% (74/509)

When you look at the bigger picture of all break points Isner faces, not only the break points he saves, the 6’10” American serves an ace 23.9 per cent (187/783) of the time. The rest of the Top 20 average an ace just 5.9 per cent (1275/21662) of the time they face a break point.

The only other player who comes close to Isner is the all-time ATP Tour aces leader, Ivo Karlovic, who is currently No. 81 in the ATP Rankings. Isner has hit an ace on 33.6 per cent of break points saved since 2015, while Karlovic has hit an ace 31 per cent of the time.

The new Infosys ATP Serve & Return Tracker identifies which direction Isner has hit his aces on break point since the 2011 season. This data is sourced from 2011-2018 ATP Masters 1000s and Nitto ATP Finals.

2011 – 2019: Isner Serve Direction / Aces On Break Point

Isner clearly favours going wide to hit his aces on break point in both the Deuce court and Ad court. The most striking ratio was at Ad Out, when he struck an ace 16 times out wide and just four times down the T. It must be nice to roll the dice on break point and find an ace one out of three times this critical point is saved.

Current Top 20: Percentage of Aces Saving Break Point

Rajeev Ram and Joe Salisbury saved a set point in the first set on Friday en route to a 7-6(4), 6-4 victory over Dutch wild cards Robin Haase and Matwe Middelkoop in 73 minutes at the ABN AMRO World Tennis Tournament in Rotterdam. Ram and Salisbury, runners up at the Brisbane International (l. to Daniell/Koolhof) in January, saved one set point on a deciding point at 5-6, before putting together a strong performance in the tie-break.

They will next play Jean-Julien Rojer and Horia Tecau, the 2015 titlists, who won 86 per cent of their first-service points to defeat Wesley Koolhof and Jurgen Melzer 6-1, 6-2 in 62 minutes. Rojer and Tecau have an 18-5 team record in tour-level finals.

Gael Monfils extended his run of form by reaching an ATP Tour semi-final for the second consecutive week on Friday with a 6-1, 6-2 victory over Damir Dzumhur of Bosnia and Herzegovina in 70 minutes at the ABN AMRO World Tennis Tournament in Rotterdam.

“It was a good one,” said former World No. 6 Monfils. “I stuck to my game plan and I am satisfied how I executed. I prepared well in the off-season and I am starting to believe that I can get back to the top of the game.”

The Frenchman will next challenge fifth-seeded Russian Daniil Medvedev, the player he lost to in last week’s Sofia Open semi-finals, or Sunday’s Open Sud de France champion and 2017 Rotterdam titlist Jo-Wilfried Tsonga of France.

Dictating with his forehand, 2016 Rotterdam finalist Monfils upped the ante on Dzumhur’s serve in the fourth game of the first set, and the Frenchman earned a second break for a 5-1 lead when Dzumhur mis-timed a drop shot. Monfils wrapped up the 38-minute opener when Dzumhur struck a backhand volley wide.

A lapse in concentration, on a forehand volley, cost Dzumhur the first game of the second set, as Monfils ripped a forehand winner past him. Dzumhur’s level improved and a wild fourth game saw Monfils lose his advantage, but the World No. 33 immediately regrouped at 2-2 and went on to complete his seventh win in nine matches in 2019. Monfils also beat Dzumhur 6-0, 6-4, 6-0 in the Australian Open first round last month.