The Argentina frontman made an immediate impact after coming off the bench, scoring 19 minutes from time to maintain the Nerazzurri's already unassailable advantage at the summit.

The goal was a bitter blow for the Sicilians, for whom Arturo Di Napoli's penalty had been saved by Francesco Toldo only few minutes earlier.

Messina are now 10 points adrift of the last position of safety with only three games remaining.

The hosts started brightly, holding onto the ball well against the newly-crowned Serie A champions.

Messina were attacking quickly, with Toldo deflecting Alessandro Parisi's shot from the left out for a corner in the 19th minute.

Inter's first opportunity of note arrived midway through the first half when Alvaro Recoba's corner landed on the head of Mariano Gonzalez, but his effort was way off-target.

Four minutes later, Marc Zoro tried his luck with a fierce low free-kick for the hosts which flew wide.

Manolo Pestrin also lined one up from distance just before the half-hour mark as the home side continued to push for the opener, but he too failed to trouble Toldo.

Roberto D'Aversa then took advantage of a strange bounce in the Inter penalty area to seize possession and shoot, only for his strike to arrow wide of the far post.

D'Aversa had a go from a central position moments later, which Toldo was equal to.

Di Napoli produced a lovely lob over Toldo five minutes before the break, but his effort was also marginally too high to find the net.

Recoba's shot in first-half injury time was all Inter could offer in what remained of the opening 45 minutes.

Messina continued to seek the breakthrough after the interval, with Luigi Lavecchia making space for a shot from just outside the area which Toldo did well to save.

Recoba again did his best for Inter from long range but could not find a way past Gabriele Paoletti.

Marco Zanchi passed up a fantastic chance to give Messina the lead in the 50th minute, but was off-balance when he shot and could not find the target.

The hosts' desperation to get a goal which would keep their survival hopes alive saw gaps opening up at the back.

Inter looked to capitalise, with Recoba's long ball finding Gonzalez alone in front of goal only for his shot to miss its target.

Messina's next opportunity came from a Vincent Candela free-kick which flew just wide.

The home side were gifted a golden opportunity to take the lead in the 69th minute when the referee pointed to the spot following handball by Marco Andreolli. But Toldo saved Di Napoli's penalty.

And Roberto Mancini's champions duly made their hosts pay for that miss two minutes later.

Crespo, who had only been on the pitch a matter of 60 seconds in place of Santiago Solari, converted a cross by fellow substitute Luis Figo to put Inter ahead.

Inter then had their tails up and could have made the margin of victory bigger in the closing stages, with Figo and Patrick Vieira shooting wide.

There were to be no more goals, but Inter had done enough and Messina were left to ponder what might have been.