Andy Murray will miss next week's Estoril Open in Portugal after the back injury which forced him out of the Monte Carlo Masters failed to clear up.
Murray has just broken into the world's top 10 players
The Scot, who turns 20 on 15 May, told his own website he wanted to come back stronger to prevent a reoccurrence.
"I started hitting again too soon to see if I'd be OK for Estoril. It looks like I'll have to miss it," he said.
"Rome and Hamburg are the big ones before the French Open and I want to make sure I'm ready for them."
Murray has just broken in the world's top 10 for the first time before he was hit by back spasms while playing doubles with his brother Jamie in Monaco.