It was literally from Eaton Park to Paris for the 21-year-old as the previous weekend he had lined out for Ballymena in an AIB League Division One clash with Old Belvedere.
It was a similar scenario for young flanker Willie Faloon, who made his Ulster bow as a replacement against Stade after impressing for AIB League Division Two challengers Ballynahinch.
After the game, Ulster coach Matt Williams paid special mention to these young talents and Whitten in particular.
"We had a lot of young players in there who stood up to the test. Ian Whitten was comfortably the best centre out there," he observed.
"I thought he had a magnificent game and overshadowed Gasnier by a considerable margin.
"His kicking game, how he entered the line, his offloading.
"That's the first time he's run on a senior field. He was phenomenal."
Of course, Ulster half-backs Ian Humphreys and Paul Marshall have also had run-outs this season with Ballymena and Belfast Harlequins respectively, while Ireland prospect Darren Cave was a regular in the 'Quins midfield up until he nailed down a starting spot in Williams' side.
This encouraging movement of players from the club scene into the provincial set-ups just backs up how important the AIB League is and will continue to be, giving that initial 'leg up' to our Test stars of the future.
It is an ongoing and mutually benificial process. It takes time and patience for the opportunity to come and Whitten is likely to be back in the Ballymena line-up for their trip to Blackrock College this weekend.
In the other provinces, seeing provincially-contracted players listed on AIB League club teamsheets is a common occurrence.
Just last Saturday, Leinster out-half Jonathan Sexton was helping St. Mary's College get the better of Old Belvedere at Anglesea Road and the Munster and Ireland-capped quartet of Denis Leamy, Mick O'Driscoll, Anthony Horgan and Frankie Sheahan have all donned the Cork Constitution colours this season.
That is what makes the AIB League still such a vital competition on the landscape of Irish rugby. There is room for everyone, from gnarled club veterans to experienced pros, from hard-hitting imports to the homegrown heroes fresh out of school or college.
Adding to the feel-good factor in the league is noting the number of players from Ireland's 2007 Under-20 squad that are currently flourishing at clubs around the country.
Shane Monahan, the current top try scorer in Division One (nine tries), heads the pile as Blackrock's prolific winger. There is hooker Richie Sweeney at St. Mary's College, full-back Felix Jones at Old Belvedere and scrum half Paul O'Donohoe at Clontarf.
Away from the capital, Young Munster's Ger Slattery is another hooker on the rise, versatile back Aidan Wynne is a favourite at Buccaneers and forward trio Andrew Browne (Galwegians), Neilus Keogh (UCC) and Eoghan Grace (Shannon) are all making their mark at their respective clubs.
And of course the captain of that Irish Under-20 side, flanker David Pollock has starred for Queen's and Dungannon in recent seasons before establishing himself in the Ulster squad.
The conveyor belt of talent is there to be seen. Only a percentage will make the cut as regular provincial and senior international players but the systems are in place to ensure that most will get a fair cut at reaching a higher level.
One man who has been at that higher level is Jason Holland, the former Ireland 'A' centre who is currently Munster's backs coach and also player-coach of AIB League Division Three outfit Midleton.
His commitment to the Cork club is admirable and like many players, volunteers and coaches in the four provinces, 'Dutchy' has become one of the league's unsung heroes.
Fresh from giving his coaching input to Munster's fine win over Sale Sharks recently, the following afternoon he donned the number 10 jersey for Midleton and steered his side to a muddied 22-0 win over Corinthians. All in the line of duty and another example of what makes the AIB League what it is.