And the former Munster boss, who knows all about O'Driscoll from his time in Ireland, has no doubt that the 34-year-old centre will be one of Warren Gatland's key lieutenants in June and July despite critics suggesting O'Driscoll is past his mercurial best.
"O'Driscoll is a player who can win a match with one moment of magic and I am certain he will be a part of the touring party that travels to Australia," McGahan told the Irish Independent.
"If Brian is fit then he will, I am sure, be a big part of the Lions tour.
"Brian is a player who commands huge respect on this side of the world. What he has achieved with Leinster and, in particular, with Ireland is well known in Australia.
"He is a player who has certainly been a marvellous player for a long number of years and he continues to be."
Another star McGahan expects to see again later this year if he can prove his fitness is 2009 Lions captain Paul O'Connell.
O'Connell was McGahan's skipper at Munster but is currently sidelined with a back injury.
The giant second row's planned return in April leaves him with little time to convince Gatland of his selection credentials yet McGahan feels a few good games without a setback could be enough to secure a hat-trick of tours for the 33-year-old.
"Paul has been compromised because of injury these last few years," added McGahan.
"I don't know how things are with him other than what I have read.
"Having a back operation is a serious thing, but if he's fit and playing well there are few around who are better than Paul O'Connell."