Roger Federer will play two warm-up events to help him prepare for the defence of his Wimbledon and embark on reclaiming the world number one ranking.
The 36-year-old has not played since losing to Thanasi Kokkinakis at the Miami Open, after choosing to skip the entire clay court season for a second consecutive year.
That defeat saw Rafael Nadal return to the top of the ATP standings, though the Spaniard relinquished the position temporarily after losing to Dominic Thiem in Madrid.
But victory at the Italian Open and his 11th French Open title, claimed after beating Thiem in straight sets, has seen Nadal return to the summit of mens tennis.
This week sees Federers much-anticipated return to the sport at the Stuttgart Open, where last year he was dumped out in the first round by Tommy Haas.
“Its not always that easy, especially on grass,” Federer said on his return.
“The rallies are short, a few points decide them. It was like that two years ago against Dominic Thiem and last year I lost against Tommy Haas after having a match point.
“When its wet it gets slippery pretty quick and you are afraid to slip. Once you play timidly all the good practice was for nothing and your good game is gone.
“In the last two years I lost against good players, so it also always depends on your opponent. The grass doesnt only look good, but is really perfect.”
Should the 20-time grand slam champion reach the final at the Mercedes Cup, something he has never previously done, he will replace Nadal as world number one.
To stand any chance of starting Wimbledon at the top seed he must also retain his title in Halle.
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It remains to be seen whether Nadal will play any tune-up events before Wimbledon, which begins on 2 July, and that could be dictated by the severity of the wrist injury which hindered his campaign at Roland Garros.
Bar playing two exhibition matches on grass to prepare for Wimbledon, Nadal rested completely after winning his 10th French Open.
His performance at SW19 was affected as a result, as he reached the fourth round before losing to Gilles Muller.