The on-loan Chelsea forward was hurt while heading home the winner in Saturday's Premier League clash at West Ham but was able to continue and could even play some part in Tuesday night's Capital One Cup tie at Fulham.
Martinez said on Monday: "Romelu is fine. We were in yesterday and the reaction has been great.
"The medical department are very happy with him, so there are no concerns with Romelu.
"We will keep on top of him but there is no reaction. He trained and he is ready to carry on as normal.
"He had that incredible impact on Saturday with the start of a new career at a new club.
"It is one of those good feelings you want to carry on and we are really pleased to have him in that frame of mind."
Gibson set to return
Martinez was also pleased to confirm that central midfielder Darron Gibson will be fit to return from injury at Craven Cottage.
"Darron I consider fully fit," said Martinez.
"He has been working extremely well and has joined the group, so that is a great positive for us."
Arouna Kone missed the West Ham game after a knee problem but Martinez added: "He was 95% at the weekend and we didn't want to take the risk. There is a 99% chance he will be available."
Martinez will be resting some players in the cup tie and added: "I think every game that you play in an official manner is an important game but, what is important, is that we understand we have to share the demands within the squad, and I do feel this squad is ready to cope with that.
"But I expect a real good performance whichever team is on the pitch.
"We are desperate to get through but it will be a great opportunity for certain players to show what they can do. The squad is big enough to be able to give the time to the players who need to recover."