Stefanos Tsitsipas will play singles and doubles in Mallorca.
"I would say the game of everybody become more beautiful [on grass]," Carlos Alcaraz said.
The 27-year-old Estonian reached a career-high rank of No. 2 last June.
"I’m really sad to have to withdraw from the tournament, and not get the chance to defend my title," Matteo Berrettini said.
Want to work at the 2023 US Open? Head to Louis Armstrong Stadium this month.
"I'm still dealing with a couple of things in my knee," Wimbledon finalist said.
Andy Murray has posted 10 consecutive grass-court wins.
