Messi has not played since injuring his hamstring against Betis in early November, but scored a superb hat trick in a training match earlier this week after returning to Catalunya following recovery work in Argentina.
Although he has been left out of the squad to face Elche on Sunday, Martino is confident the Argentine star will soon be ready for first-team football.
"He's come back really well, he's had three good training sessions. He has the look of a killer," Martino said of the 26-year-old at a press conference. "He's lacking the rhythm of training with his teammates, he's done more work with the ball.
"We are looking at when he will be ready to play."
Martino has largely a full squad to choose from for Sunday's encounter, with Victor Valdes included in the matchday squad after recovering from injury.
The manager admits his side will now be expected to perform at its very best in its return from the winter break.
"The squad have come back really well," he said. "We've got everyone back. That always raises expectations when you have the chance to chose from a rich squad."