Juan Martin del Potro was challenged in his first match of the North American hard-court swing, but the top seed still advanced, saving five of seven break points en route to a 7-5, 6-3 victory against American qualifier Marcos Giron at the Abierto Mexicano de Tenis Mifel presentado por Cinemex in Los Cabos.

Del Potro was contesting his first match since falling in the Wimbledon quarter-finals to Rafael Nadal. The 25-year-old Giron, meanwhile, had fought through qualifying and his first-rounder in Los Cabos.

The Argentine will next face Belarusian Egor Gerasimov, who stunned fifth seed and defending champion Sam Querrey of the U.S. 7-5, 5-7, 7-6(6), overcoming 23 Querrey aces to advance in exactly two hours. The 25-year-old Gerasimov is No. 301 in the ATP Rankings and had not won a tour-level match this year before Los Cabos.

Brit Cameron Norrie made it back-to-back ATP World Tour quarter-finals by beating Feliciano Lopez of Spain 6-3, 6-3. Norrie reached the Atlanta semi-finals last week (l. to Harrison). He will next meet fourth seed Adrian Mannarino, who dropped only two games against Sweden’s Elias Ymer 6-0, 6-2.

A pair of #NextGenATP Americans had mixed fortunes. Michael Mmoh, 20, reached his second ATP World Tour quarter-final of the year (Brisbane) with a 7-6(1), 7-6(2) victory against Canada’s Peter Polansky. Mmoh will next meet Bosnian Damir Dzumhur of Bosnia. The third seed beat Italy’s Thomas Fabbiano 7-6(0), 7-6(5).

But Mmoh’s countryman seventh seed Taylor Fritz fell to Japan’s Yoshihito Nishioka 7-6(3), 6-1. Nishioka will meet Italy’s Fabio Fognini or Quentin Halys of France in the quarter-finals.

Kei Nishikori has set a blockbuster third-round Citi Open showdown with #NextGenATP Canadian Denis Shapovalov. The Japanese No. 7 seed beat qualifier Donald Young and the onset of heavy rain to win his opening match in Washington, D.C. on Wednesday night.

In his first match since reaching the quarter-finals at Wimbledon, the 2015 Citi Open champion posted his seventh victory from as many FedEx ATP Head2Head meetings with the American, 6-3, 6-4 before rain returned to wash out the night’s remaining matches.

Fit and healthy again after an ongoing wrist injury, Nishikori has made no secret of his desire to return to the Top 10 in the ATP Rankings by the end of the season, and he looked every bit the Top 10 player he once was against Young. The 28-year-old’s 22 winners more than doubled his opponent’s, and he dropped just seven points on his first serve.

Young was coming off an impressive win over former World No. 3 Stan Wawrinka in the opening round, having won through qualifying to reach the main draw. The World No. 234 did not drop serve once against Wawrinka but was broken twice against Nishikori. Despite having pegged back a break in the third set, he surrendered serve on a string of loose errors at 4-4 before the No. 7 seed served out the result in 84 minutes.

Earlier, No. 3 seed David Goffin rallied from 3-5 down in the third set to deny Frenchman Pierre-Hugues Herbert in a two-hour-plus thriller. Both men broke five times during the match but it was the Belgian who prevailed 6-2, 1-6, 7-6(5) to set up a third-round clash with #NextGenATP American Frances Tiafoe.

Mischa Zverev knew something was up. His younger brother, Alexander Zverev, said to him, “Check out the draw.”

“Why,” Mischa said.

“Check it out,” Sascha said.

Sascha had seen what ATP World Tour fans circled when the Citi Open draw was released: The possibility of the Zverev brothers playing each other in a tour-level match for the first time. And it was a good possibility: Each just needed to win a match.

The brothers batted away any hype, leaning on clichés. Mischa Zverev: “You never know. You don’t want to look too far ahead in the tournament.”

Sascha Zverev: “We don’t have easy opponents.”

But at last, after a combined 539 main draw matches between the two, the Zverev brothers will meet in a tour-level contest. Sascha finished off Malek Jaziri of Tunisia on Wednesday evening, winning the second set of their rain-postponed match to advance 6-2, 6-1. Earlier in the day, Mischa beat American wild card Tim Smyczek 6-2, 7-6(6).

“I think it’s going to be an interesting day,” Mischa said.

“We’re definitely excited,” Sascha said.

The two have played twice before but in qualifying matches, and Mischa, who is nine years older than Sascha, won both of them (2012 Dallas, 2014 Houston).

“One is when I was 14 years old, so that doesn’t really count,” Sascha said, “and the other time when I was 15 and a half. It was a very, very long match… and at some point, because I was quite skinny still and not very fit, I started cramping in the third set, 3-2, so I retired.”

Sascha is 21 now, though, the defending champion at the Citi Open and the No. 3 player in the ATP Rankings. His older brother isn’t too shabby, either, as the 15^th seed in Washington and at No. 43 in the ATP Rankings.

“It’s nice because we’re finally at a point where, we’re at a big tournament, we both play decent tennis,” Mischa Zverev said. “I think it’s a win-win situation because it means both of my parents did a good job. They raised decent tennis players, and it’s going to be a win-win no matter what.”

The top four seeds — Dominic Thiem, Philipp Kohlschreiber, Fernando Verdasco and Robin Haase — at the Generali Open all made second-round exits on Wednesday.

Slovakian qualifier Martin Klizan recorded the fourth Top 10 victory of his 12-season pro career (4-18 lifetime). Klizan beat 2014 finalist Thiem, currently No. 8 in the ATP Rankings, 1-6, 6-1, 7-5, breaking in the final game of their two-hour Kitzbühel encounter. Klizan is now 3-0 in their FedEx ATP Head2Head series.

“The first set was really bad, but then I played better,” said Thiem. “Sets two and three were okay, [but] it’s very bitter for me. The atmosphere was great in the stadium today, there were some good rallies. It could have been a great start into the tournament, but losing it in the end is very disappointing.”

Klizan will next challenge eighth-seeded Serbian Dusan Lajovic, who lost just four of his first-service points to beat wild card Dennis Novak of Austria 6-2, 6-4 in 68 minutes. Lajovic reached the Kitzbühel semi-finals in 2016 (l. to Basilashvili).

Earlier in the day, Uzbekistani qualifier Denis Istomin got the better of second seed Kohlschreiber for the second time this year (also MercedesCup) with a 5-7, 6-3, 6-1 win in two hours and nine minutes. Istomin, who let slip a 5-3 lead in the first set, will now face another German, sixth seed Maximilian Marterer, who lost seven of his first-service points to defeat Mikhail Kukushkin of Kazakhstan 6-3, 6-4 in 74 minutes.

Chile’s Nicolas Jarry reached his sixth ATP World Tour quarter-final (or better) this year by overcoming third-seeded Spaniard Verdasco 6-7(6), 7-5, 6-3 in two hours and 12 minutes. Jarry led 6/3 in the first-set tie-break, but regrouped for his 21st win of the year. He will now play Italian Matteo Berrettini, last week’s J. Safra Sarasin Swiss Open Gstaad titlist, who beat Radu Albot of Moldova 6-3, 6-7(3), 6-1 in just under two hours.

Spaniard Jaume Munar knocked out fourth-seeded Dutchman Haase, the 2011 and 2012 champion, 7-6(5), 6-4 in one hour and 36 minutes. He’ll next play Japan’s Taro Daniel, this year’s TEB BNP Paribas Istanbul Open (l. to Jaziri) finalist, who beat Laslo Djere or Serbia 6-3, 6-2 in 76 minutes.

In-Form South Americans Begin Doubles Campaign
Top seeds Julio Peralta and Horacio Zeballos, going for their third ATP World Tour crown in as many weeks, got their Kitzbühel campaigns off to a winning start with a 6-3, 7-5 victory over Kevin Krawietz and Hans Podlipnik-Castillo. Over the past two weeks they have captured trophies at the SkiStar Swedish Open (d. Bolelli-Fognini) and the German Tennis Championships 2018 presented by Kampmann (d. Marach-Pavic).