The world's most-capped player with eight more international appearances than O'Driscoll, the star scrum-half is quick to dismiss claims that BOD is 'past it' and he remains convinced that the 34-year-old centre could make another lasting impression Down Under.
"What has caught my eye over the past seven or eight weeks? Well, first Brian O'Driscoll," Gregan wrote in the Telegraph as part of his role as an HSBC Ambassador.
"I have always been a huge fan and you can just see from how he bounced back from a serious ankle injury in the autumn how hungry he still is and a big part of that is the possibility of one final Lions tour.
"In the modern day, a fourth Lions tour, revisiting Australia 12 years after he made his Lions debut, would be a special achievement. I would be very surprised if he is not right in the mix and then heavily involved come the big matches.
"As you start getting towards the back end of your career, and I talk from some experience, it becomes more of a mental thing. Obviously you have to take care of your body but as a professional rugby player that should be a given.
"The trick is being hungry and fresh mentally. Brian still has that in buckets. He still loves winning and hates losing. He still wants to be inside the arena not outside."
While O'Driscoll has already been written off in some quarters, others are predicting that he will be handed the ultimate honour on April 30 by being named captain of Warren Gatland's tourists
Gregan knows all about skippering the elite having led the Wallabies but he insists O'Driscoll will play a key role in the dynamic of the tour regardless of Gatland's call on the captaincy.
"All you can say about O'Driscoll is that he is a natural leader and, whether he is wearing the captain's armband or not, he will automatically be a leader within that senior group of players that shape such tours," added Gregan.
"I would not get too hung up on the captaincy issue, although it makes for a good debate among the fans. It is entirely down to Warren Gatland, it is his call and we do not know all the factors that come into play.
"I can see 'leaders' dotted liberally across most positions for the Lions."