According to Irvine, Schumacher is not only fit enough to mix it with today's young guns, but more than capable of winning races and challenging for the title in 2010.
Schumacher was close to returning to Formula One with Ferrari in 2009 before a neck injury scuppered his comeback. But Irvine exclusively told ESPNF1 that Schumacher was already infected with the F1 bug during his role as an advisor with Ferrari, and that a more permanent move back to the sport was merely a matter of time.
"I think he was bored," said Irvine. "When he was going to the races with Ferrari he was probably thinking 'what the hell am I doing here?' There was no point in him going to the race as an advisor because he didn't know enough of that side of the business, so he really didn't have a proper job and was just turning up as a poster boy.
"He would have come back with Ferrari but he definitely had a bad problem with his neck. I was playing poker with him in Milan, and he had to turn his shoulders to look left or right to talk to people. But he's obviously hired the best physios and time has healed the problem."
And when Schumacher does climb into the cockpit of his Mercedes on the grid for the start of the 2010 Bahrain Grand Prix, the 41-year-old will be mixing it with the likes of Sebastian Vettel and Lewis Hamilton , both nearly 20 years his junior. But Irvine, who was Schumacher's team-mate from 1996 to 1999, is certain that he will be able to challenge today's young guns for wins.
"Fitness won't be an issue," he said. "Look at Nigel Mansell who was a big fat blob and he won the world championship in 1992 aged 39. Michael is fast enough to win races again and there is absolutely no comparison between Michael and Jenson Button in terms of ability. Jenson won the world title this year so Michael can win it next year in the right car and even if he doesn't have a competitive car, I don't think Michael will get disheartened. He just loves to race and is a very hard-working, patient guy who won't get upset if things don't happen overnight.
"Everything fell into Brawn's lap in 2009, but 2010 is going to be tougher. Ross is no mug and with Mercedes behind him, they will get it right. Michael went to Ferrari when they were in a far worse position than Brawn was in 2009 and managed to turn things around for them."
He believes that fellow Mercedes driver Nico Rosberg will be facing a daunting task against his vastly more experienced team-mate. Although he does not subscribe to the theory that Schumacher has ever entered a team as the automatic No. 1, he does not think it will take long for normal service to be resumed.
"Michael won't walk in there and expect to be No. 1 to Nico. The fastest guy will be the No. 1 and that's always been the case wherever Michael has been. If Nico goes quicker than him then he can expect to be team leader but I don't expect that to happen.
"When I was at Ferrari with Michael, I did the majority of the testing, the tyre work and the chassis work. But Michael could just get in the car and go fast immediately. He was quicker than me so he was the No. 1. When I was close to winning the title in 1999, Michael came back after his broken leg and proved he wasn't just the best No.1 but also the best No. 2 in Malaysia when he let me past for the race win."
With newly-crowned world champion Button moving to McLaren to form an all-British dream team with 2008 champion Hamilton, the announcement of Schumacher's return to the sport adds further intrigue to what is already one of the most eagerly-anticipated seasons in recent memory. Even at this early stage, Irvine has very clear ideas of who he expects to come out on top and it does not make for good reading for the current world champion.
"Jenson has entered the lion's den - it was madness of him to move. He thinks he's going to be able to eat his steak and that's not going to be the case. I think he's going to get murdered! It's the worst decision he could have made. The only reason I can think of is that he didn't want to stay at Brawn with Rosberg, who's not as highly rated as Lewis but might be just as quick. Jenson may have thought that it's better to get beaten by Lewis than get beaten by Nico.
"Rubens Barrichello is a good little peddler and murdered Jenson in the second half of last season. Michael never got murdered by anyone. Lewis came into his first year in F1 and beat a double world champion in Fernando Alonso - that's a class act. If you look at Jenson's career, Ralf Schumacher beat him, Giancarlo Fisichella beat him and Rubens beat him. There are too many races where he hasn't performed, to say he's at the level of any of those guys.
"As for Lewis against Michael, Lewis isn't going to give an inch and it will be fascinating to see what happens. It's certainly going to be an amazing season!"