Having picked up the problem in training on Friday, the England international's start to the new season has been disrupted – though the Toffees boss has dismissed suggestions that he could miss as much as five months of action.
Martinez told reporters at Everton’s training ground: "It's a little bit too early to know how long he's going to be out but the reports about the five months ... where was that comment from?
"We all know it’s a partial tear and that could take a very different time depending on the player and I'm sure, with Ross Barkley, it will take a little time - possibly between seven, eight, nine weeks."
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"You would expect with such a physically strong boy that he has recovered a lot quicker in the first few days," Martinez added. "At the moment we are very, very pleased with his progress, he’s got his knee in a brace and at the moment every day is a day we are getting a lot of benefit in his recovery."
Though Barkley's injury could provoke a rush to find cover in the transfer window, the Everton boss is keen to be careful and weigh up how other injured stars like Bryan Oviedo and Arouna Kone are getting on before reinforcing further.
"There's going to be many links [but] there's a long time left in the window," he added. "We are more focused than ever to see how strong we are internally.
"It depends on how the injured players progress. We're keeping a close eye on Oviedo and Kone [and] if they're going to be immediately involved or take a little while. It's true over the next two weeks we need to take that into consideration as then the transfer window closes."
However, Martinez feels that his current squad are versatile enough to cope as they are, explaining: "We are a team that needs to be flexible in how we approach games because we have players who can adapt and be real thinkers on the pitch.
"We've never been a rigid team and you want to be able to adjust. We want to be flexible and we'll always try to have individuals who can cope with that.
"I'm delighted with the squad we have [but] we need to be a little bit open-minded with what we do in the window."