Marcos was beaten in the first round of the BNP Paribas Open on Thursday, falling to German qualifier Daniel Brands 6-0, 7-6(3). At the end of the first set, Marcos received treatment from the ATP trainer. He fought hard to be competitive in the second set, but succumbed in 88 minutes.

“My shoulder has been bothering me for two days,” explained Marcos. “I cannot serve very well and I couldn’t serve today. I couldn’t hit the ball right, push my opponent off. It’s an injury that’s been bothering me for two days, but today it was worse

“I wanted to believe nothing wrong and I tried to play. I accepted the fact I have pain in my shoulder and maybe could serve with less power and play the points. I tried to fight, but didn’t find the way to win the second set. Overall the performance was not so good.”

Marcos will have an MRI scan on Friday before making a decision on his participation in the doubles. He and Mikhail Youzhny are expecting to play their first-round match against Treat Conrad Huey and Jerzy Janowicz on Sunday.

“It’s not something I had before,” said Marcos. “It’s a bit frustrating, because I’ve been playing good lately. The pain in my shoulder wouldn’t let me play 100%.”