Roger Federer, Naomi Osaka and Maria Sharapova all kicked off their grass-court campaigns with victories in different tournaments on Tuesday.
Federer beat John Millman in straight sets to reach the second round of the ATP tournament in Halle. The world No 3 won 7-6, 6-3 on a muggy evening to set up a second-round meeting with French veteran Jo-Wilfried Tsonga on Thursday.
"It is always important to win your first game on grass, because otherwise the grass season can be very short," Federer, 37, said.
Tsonga said it would be "something special" to face Federer after he beat compatriot Benoit Paire 6-4, 7-5. The Frenchman boasts of a perfect record against the Swiss on grass, having won their only meeting on the surface in 2011.
"I am happy to have won because Benoit is a dangerous player. It is always difficult to dominate against him, you always feel like the game can change at any moment," Tsonga, 34, said.
Last year's winner Borna Coric eased to a 7-6, 6-3 win over Spain's Jaume Munar to reach Round 2.
World No 1 Naomi Osaka was tested by Maria Sakkari in her first-round match at the Nature Valley Classic in Birmingham, but eventually went through to the last 16 with a hard-fought 6-1, 4-6, 6-3 win.
In her first match since her third-round exit at French Open this month, Osaka, 21, struggled with her first serve against the world No 33 and took two hours to dispatch her Greek opponent.
However, the Japanese, who lost to Sakkari prior to her US Open title run last year, fired seven aces and won five break points to clinch victory on a surface she had previously conceded was not her strongest.
Former French Open champion Jelena Ostapenko stormed into Round 2 with a 6-0, 6-2 demolition of Iga Swiatek.
Elsewhere, Sharapova made a winning return from injury by beating Viktoria Kuzmova 7-6, 6-0 to reach the second round of the Mallorca Open. The five-time grand slam champion has not played since the end of January after taking time out to recover from a shoulder injury, but edged a tight opening set against Kuzmova before strolling through the second.
"It's my first win in about three or four months," Sharapova said. "It's great to be here in Mallorca. What a great place to train and have a warm-up tournament."
Sharapova's ranking has dipped to 86 during her absence, meaning the Russian needed a wild card to enter the draw in Mallorca, her fourth tournament this year.
Meanwhile, the Queen's club will attempt to play catch-up on Wednesday after rain washed out a full day’s play for the first time since 2012.
