Howard has been out of action since picking up a calf strain just before half-time of the December clash against Stoke, but is expected to return to the pitch in the coming week after resuming full training.
Robles has been deputising in the meantime and, after a few tense performances to begin with, has won over both the fans and media alike in recent games with his new-found confidence between the sticks.
On a run of three successive clean sheets – the same amount as Howard has recorded in his 18 Premier League starts this season – some have suggested that the Spaniard should keep his spot even when his teammate returns, but Martinez hasn’t quite bought into that argument at this point.
“I thought Joel did very well the last three games,” he said. “But Tim at the moment is the number one and whenever he is fit he needs to lose that position.
“Medically he probably needs another week but he has been training the last two days and feels that he is ready.
“I wouldn’t say one way or the other but he is very, very close and Tim is the number one and then it’s just down to the competition from Joel and it’s great to see Joel performing the way he has done.”
Robles, 24, signed for Everton from Atletico Madrid in the summer of 2013, having worked with Martinez at Wigan Athletic on a six-month loan stint which saw him help the Latics lift the FA Cup.
With Howard, who is set to turn 36 in March, seeing his form over the first half of this season come in for some criticism, the US international should be concerned if Martinez allows his compatriot a fair chance to compete for the job further down the line.