The Belgium striker has scored 18 times this season but missed the 1-0 win over Southampton and is rated only 50-50 for this weekend’s trip to Swansea.
Martinez said the 21-year-old will not return until they are 100 per cent sure his hamstring injury is fully healed, which means Arouna Kone – with just one goal in 20 appearances in an injury-ravaged two seasons at the club – is likely to start up front at the Liberty Stadium.
Steven Naismith has nine goals this season but only one of those came since early January, which is the same as Kevin Mirallas who has not featured for a month following a leg injury.
“Romelu is a massive player for us and it would be a worry if we were not to miss him,” Martinez said.
“At the moment he is still 50-50 because it is an injury we need to make sure is 100 per cent well healed before we put him on the pitch.
“It is not a major problem and he has been working well the last two days even though he hasn’t joined the group yet.
“The scoring threat Rom brings to the side is unique and we don’t have a like-for-like replacement in that respect but we have other players who have shown they can bring a different way of playing and can be as effective.
“Arouna Kone is fully fit and I feel in the last three games in the league he is showing to be himself. There are other players around who can take responsibility for not having Romelu on the pitch.”
Meanwhile, midfielder Darron Gibson has been ruled out for the rest of the season after breaking a metatarsal in training, another injury for the Republic of Ireland international who came back in September after a year out following a knee ligament injury.
“I don’t think we are going to see Darron this season. I am not worried about that, my only focus is he can recover 100 per cent and can get back with no worries of needing extra surgery at the end of it,” Martinez said.
“If he can come back in pre-season and be fully-fit for the next campaign I would be delighted.
“It is a massive blow. As a footballer, the biggest moments you need to get through are when you are injured and because there is nothing you can do about it.”