Everton manager Roberto Martinez has admitted that he is "concerned" by Lacina Traore's current hamstring injury.

The striker, who is on loan from Monaco, suffered the problem in the warm-up before Saturday's defeat to Chelsea in the Premier League.

Martinez has now revealed that the Ivorian is likely to be sidelined for a "long period".

"It is going to take a long period of time which at this stage of the season will be a big miss. It will be weeks rather than months," the Spaniard told the club's official website.

"We are a little bit concerned. We are working with his parent club and making sure we get the right diagnosis. Lacina was really down after and we need to support him. We will find out over the next 48 hours how we will treat the injury."

Everton return to action this Saturday when they host West Ham United in the Premier League.