The Top 10 are under siege.

As a collective unit, they are not enjoying the same success this season as they did last year when attempting to win the opening point of their service games.

An Infosys ATP Beyond The Numbers analysis of the current Top 10 in the Emirates ATP Rankings uncovers an almost two percentage-point drop in the Top 10 forging ahead to 15/0 compared to falling behind 0/15 when serving.

In fact, eight of the current Top 10 players are performing worse during the opening point of their service games this year compared to last year. The standout is current World No. 5 Rafael Nadal, who has improved almost five percentage points in 2017 compared to 2016.

The 30-year-old Spaniard is 29-5 through the first four months of this season. The left-hander claimed his 10^th title at both the Monte-Carlo Rolex Masters and the Barcelona Open Banc Sabadell last month.

Read More: Nadal Wins 10th Barcelona Title

The only other player to be in positive numbers in 2017 compared to 2016 is No. 7 Kei Nishikori, who has improved by almost two percentage points.

Top 10 2017 vs. 2016: Percentage of Winning The Opening Point On Serve

The peak performer in the current Top 10 in 2017 is Roger Federer, who is winning the opening point of his service games nearly 69 per cent of the time, with Nishikori in second place at about 68 per cent.

Federer was actually at 73 per cent last season – second to only Milos Raonic, who was head and shoulders above the pack at 74.5 per cent. Nadal was the worst performer out of the current Top 10 during the 2016 season, winning the opening point of his service games only 61.4 per cent of the time.

Navigating from love-all to 15/0 is more challenging so far this season for the Top 10 – a small chink in their armour where opponents are enjoying increased success.

Second seed Roberto Bautista Agut escaped from the brink of defeat on Wednesday at the BMW Open by FWU, rallying from 3-5 in the deciding set to reach the quarter-finals over Marius Copil 4-6, 7-6(3), 7-5.

The Romanian Copil captured the lone break of serve in the opening set at 2-2, but Bautista Agut came back from an early break down in the second set and dominated the tie-break to force a decider. Copil served for the match at 5-3 in the final set and came within two points of winning, but the Spaniard fought back to win the final four games and prevail in two hours and 28 minutes.

He improves his FedEx ATP Head2Head against Copil to 2-0 and looks to surpass his best Munich performance of a semi-final finish in 2015 (l. Murray).

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Awaiting him in the quarter-finals is German qualifier Yannick Hanfmann, who delighted the home crowd with a 7-6(5), 4-6, 7-5 win over eighth seed Thomaz Bellucci. The 25-year-old German saved a match point with Bellucci serving for the contest at 5-4 in the final set before ultimately scoring the upset in two hours and 19 minutes.

Hanfmann, currently No. 273 in the Emirates ATP Rankings, is making his ATP World Tour main draw debut this week. His best result this season prior to Munich was a quarter-final showing at the ATP Challenger Tour event in Bergamo.

Joining him in the quarter-finals is seventh seed Jan-Lennard Struff, who prevailed in an all-German battle against Tommy Haas 6-4, 7-5. Struff rallied from 1-3 down in the second set to win the first FedEx ATP Head2Head meeting between these players. Struff has been in fine form this clay season, reaching the quarter-finals in Marrakech and defeating Grigor Dimitrov en route to a third-round showing in Monte-Carlo.

Next up for him is third seed and #NextGenATP German Alexander Zverev, who defeated Jeremy Chardy 6-4, 6-4. The battle was a rematch of their quarter-final this February in Montpellier, which saw Zverev prevail in three sets. The German, who reached the semi-finals last year in Munich, improves his FedEx ATP Head2Head against Chardy to 3-0.

DOUBLES

Third seeds Juan Sebastian Cabal and Robert Farah are the first team to reach the semi-finals after a 6-2, 6-4 win over Italians Fabio Fognini and Andreas Seppi.

In first-round doubles action, top seeds Oliver Marach and Mate Pavic needed just 56 minutes to defeat Dino Marcan and Tristan-Samuel Weissborn 6-3, 6-2. They’ll play last week’s champions in Budapest, Brian Baker and Nikola Mektic, who moved past Julian Knowle and Alexander Peya 7-5, 4-6, 10-5.

Fourth seeds Julio Peralta and Horacio Zeballos eased past French duo Julien Benneteau and Jonathan Eysseric 6-3, 6-4. Next up for them is Mikhail Kukushkin and Sergiy Stakhovsky, who defeated Nenad Zimonjic and Mischa Zverev 6-4, 7-5.

German wild cards Gero Kretschmer and Alexander Satschko scored the upset of the day over second seeds Treat Huey and Max Mirnyi 7-6(2), 6-1, and will play the French duo of Chardy and Fabrice Martin.

Top seed Pablo Carreno Busta earned his first win against countryman Tommy Robredo, moving into the Millennium Estoril Open quarter-finals with a 7-6(5), 7-5 victory on Wednesday.

The 25-year-old Carreno Busta hadn’t won a set and was 0-3 against the 35-year-old Robredo during their FedEx ATP Head2Head series. But all three of their past match-ups took place in 2014, and Carreno Busta has leaped in the Emirates ATP Rankings since their most recent contest, a quarter-final at Umag in 2014.

At the time, Carreno Busta was ranked No. 57 and hadn’t reached an ATP World Tour final. Nearly three years later, though, the 6’2” Spaniard is ranked No. 21, has reached five finals and won two ATP World Tour titles (Moscow 2016; Winston-Salem 2016).

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Carreno Busta, an Estoril semi-finalist in 2015 and a finalist in 2016, will face another veteran countryman in the last eight: defending champion Nicolas Almagro, who dropped only two points on his first serve (20/22) to beat Portugal’s Gastao Elias 6-1, 6-2. Almagro improves to 9-1 in Estoril.

Second seed Richard Gasquet won his first tour-level match since February, advancing to the quarter-finals with a 6-1, 6-4 victory against Argentine Carlos Berlocq. Gasquet, the 2015 Estoril champion, underwent appendicitis surgery in March and lost in his return last week at the Barcelona Open Banc Sabadell.

The Frenchman improved to 5-0 against Berlocq in their FedEx ATP Head2Head series. The 30-year-old Gasquet will next meet South African Kevin Anderson, who outlasted Portuguese qualifier Joao Domingues 5-7, 6-3, 7-5 in two hours and 24 minutes.

Fifth seed Juan Martin del Potro received some sad news and had to withdraw from the tournament to head back to Argentina. “I received the news of the death of my grandfather, and I need to go to my family to be with them during this hard time and say goodbye with them. Thank you Estoril, I will see you soon,” del Potro said in a statement.

.@delpotrojuan .@delpotrojuan is on his way to Argentina after his grandfather passed away today. He wants to stay with his family in this tough moment.

— Jorge Viale (@jorgeviale) May 3, 2017

Second seed Marin Cilic enjoyed a winning debut at the TEB BNP Paribas Istanbul Open on Wednesday as he dismissed Damir Dzumhur 6-3, 6-2 in 70 minutes.

The Croatian opened his clay-court swing with a quarter-final showing in Monte-Carlo two weeks ago (l. to Ramos-Vinolas) and is bidding to win his second title on the dirt this week, five years on from his Umag triumph.

Cilic goes on to face eighth seed Steve Darcis, who made short work of Jiri Vesely with a 6-2, 6-1 victory in 52 minutes.

Sixth seed Bernard Tomic booked his quarter-final spot with a 7-5, 6-3 victory over Rogerio Dutra Silva.

“It’s my second time being in a clay-court quarter-final,” said Tomic. “It’s a very good thing for me. This time last year I was ranked 17, 18 in the world and couldn’t win a clay-court match. It’s good progress for me. I’m happy that I’m playing well, especially in Istanbul.”