Roger Federer confirmed his participation for this year's Madrid Open, on Wednesday, marking his return to the European clay court season after two years away.
The 20-time Grand Slam champion has not played this year since his Australian Open round of 16 defeat by Greek Stefanos Tsitsipas in January.
Federer, whose sole French Open title came in 2009, has preferred to skip the European clay season over the last two seasons to manage his schedule.
The 37-year-old Swiss is the second most successful player at the Caja Magica behind Rafa Nadal, winning three titles in 2006, 2009 and 2012.
"Federer is one of the best players of all time, it's no secret," tournament director Feliciano Lopez said in a statement.
"We are happy because his return to Madrid is a gift to the tournament, but above all the fans will be able to see a unique player in the Caja Magica. Having the Swiss player back on clay with Djokovic and Nadal is going to be unmissable."
World number one Novak Djokovic and 11-times French Open winner Nadal are also expected to feature at the Madrid Open, which will be played from May 3-12.
Thiem knocked out in Round 1; Del Potro cruises
Top seed Dominic Thiem was knocked out the Rio Open in the first round on Tuesday, going down 6-3, 6-3 to Laslo Djere, a result that gave the unheralded Serbian his first victory over a top 10 player in his career.
The world ranked No. 90 broke Thiem’s serve five times in what was a surprisingly lackluster display from a man who has won eight ATP titles on clay.
Thiem served five double faults in a tournament he won in 2017.
"He played a bit worse than normally I think, to be honest," Djere said. "But I had a great day. I felt the ball really well, hitting well from the baseline and then attacking well when it was time for that."
"The biggest win in my career so I'm really happy right now."
In another upset, third seed Marco Cecchinato was beaten 7-5, 7-6(1) by Slovenian Aljaz Bedene.
Cecchinato was on a high after winning the Argentina Open on Sunday but he never hit the same heights against the unseeded Bedene.
Taiwan's Hsieh stuns Kerber to reach Dubai quarters
Wimbledon champion Angelique Kerber suffered a surprise last 16 exit from the Dubai Duty Free Tennis Championships after being beaten by unseeded Hsieh Su-wei 5-7, 6-4, 6-0 on Wednesday.
Taiwan's Hsieh was two games away from defeat when Kerber rallied from 2-4 down to draw level at 4-4 in the second set, but the world number 31 won eight of the last 10 points to send the match to a decider.
The 33-year-old Hsieh ultimately scorched into the last eight, converting three break points to bagel her German opponent.
Hsieh, who recorded her first win in three attempts against Kerber, will next face Karolina Pliskova for a place in her second semi-final of the season, and first since the opening week of 2019 at the Auckland Classic.
"How did I win? I try very hard," Hsieh said after notching up her first victory over a top 10 opponent since beating Simona Halep at last year's Wimbledon.
World number four Petra Kvitova overcame American qualifier Jennifer Brady 7-5, 1-6, 6-3 to reach the last eight in Dubai for the first time in six years.
Australian Open runner-up Kvitova was two points away from losing the opening set in the ninth game when she responded in style by clinching 14 of the next 16 points.
After defeating Katerina Siniakova in three sets in the second round, Kvitova had said on Twitter she was "glad P3tra came back" - and the two-time Wimbledon champion was forced to step up her game again in a decider against Brady.
Kvitova benefited from Brady's sixth double fault of the match to secure a break in the first game before producing a string of delightful serve and volley combinations to extend her lead.
While Kvitova squandered her first match point by producing a 10th double fault, the Czech sealed a victory with a clinical point finished at the net.
"The wind was just terrible today, to be honest," said Kvitova after reaching at least the quarter-finals for the fourth successive tournament.
"It was really difficult to find a way with it. I couldn't really serve well today at all. It's been big struggle for me."
Third seed Simona Halep joined Kvitova in the quarter-finals after the Romanian continued her steady progress with a 6-3, 7-5 win over Ukraine's Lesia Tsurenko.
Two-time defending champion Elina Svitolina extended her winning streak in Dubai to 11 matches after defeating two-times Grand Slam champion Garbine Muguruza 6-1, 6-2.
Tiafoe crashes out, Del Potro advances
Frances Tiafoe's title defense wilted but Juan Martin del Potro looked fully recovered from his knee injury to cruise to a 6-3, 7-5 win over Yoshihito Nishioka in the first round of the Delray Beach Open on Tuesday.
The third-seeded Tiafoe looked to have the match against qualifier Dan Evans in hand when he served up 6-5 and 30-love in the second set but was instead broken by Evans, whose aggressive net play frustrated Tiafoe in the final two sets as the Briton eventually prevailed 3-6, 7-6(1), 7-5.
Late drama arose when Evans served for the match up 5-4 in the third set but nerves appeared to get to him and he was broken amid a flurry of unforced errors.
But Tiafoe was broken in the next game and Evans made sure not to make the same mistake twice, winning his final service game at love to set up a second-round match against tournament wild card Lloyd Harris of South Africa.
World number four del Potro, who missed last month's Australian Open to nurse the kneecap he fractured at the Shanghai Masters, showed no ill effects in his first match of the year as he blasted 12 aces to see off baseline specialist Nishioka.
The hard-hitting Argentine is looking to pick up where he left off before the injury, when his superb play made him a finalist at the US and China Opens and helped the 30-year-old reach a career-high ranking of world number three.
Del Potro, who won the tournament in Florida in 2011, will next face big-serving American Reilly Opelka after last week's New York Open champion saw off countryman Tennys Sandgren 6-4, 6-0 earlier in the day.
Top American men's player John Isner used his blistering serve to overwhelm Canadian Peter Polansky 6-3, 7-6(4) and advance to the second round.
The second-seeded Isner fired 23 aces to Polansky's four and won 87 percent of his first serve points as he cruised to victory.
Next up for Isner is a second-round meeting with unseeded Slovak Lukas Lacko on Wednesday.
Adrian Mannarino, Andreas Seppi, Paolo Lorenzi, Jordan Thompson, Steve Johnson, Mackenzie McDonald, Guillermo Garcia-Lopez and Radu Albot also won their first round matches on Tuesday at the ATP World Tour 250 event, which is played on outdoor hard courts.