Along with three of his Mary's club-mates - full-back Kevin Nowlan, scrum half Conor McGuinness and lock Malcolm O'Kelly, who was then 'on loan' at London Irish - McWeeney made his debut against New Zealand at Lansdowne Road in November 1997.
Th All Blacks won 63-15, scoring seven tries in the process. Bye bye John McWeeney!
John had seven Leinster caps under his belt when he was capped by Ireland. He went on to play a further seven seasons with Leinster, gaining 68 caps in all and scoring 21 tries - ten of them in the Heineken Cup. He last played for Leinster in March 2005 after making 17 Heineken Cup appearances.
Back in 1994, McWeeney, playing as a makeshift second row, won a Leinster Schools Senior Cup medal on a St. Mary's College team captained by full-back Denis Hickie and coached by Brian Cotter.
Joining the past pupils club, he scored his first AIB League try at home to Garryowen in March 1997, one of five St. Mary's tries in their 35-27 victory that afternoon.
Ten seasons on, he scored two tries in Mary's win over Clontarf at Castle Avenue on January 27 last and, in doing so, became the current top try scorer in the AIB League with 56 tries to his name.
In total, John scored six league tries in 1996/97. He followed this with eleven touchdowns the following season. He now appeared on the AIB League try-scoring radar for the first time, lying in joint-17th place on the tries ladder with John Lacey (Shannon and ex-Sunday's Well).
He added four more tries in 1998/99 before crossing for ten five-pointers in 1999/2000 to finish as Mary's top try scorer in the season that the club won the All-Ireland League title.
It was in March of that season that McWeeney scored his only hat-trick of tries so far in his league career. That was a game at home to Clontarf when Mary's played their 100th league fixture.
With a four-season aggregate of 31 tries, McWeeney was now in joint-first position with Ronan Browne (Dublin University, Old Wesley and Old Belvedere) on the league's all-time top tries ladder. He had scored four more tries than his club-mate Denis Hickie and nine more than John Lacey.
During season eleven of the AIB League (2000/01), McWeeney collected three tries while Lacey picked up 13 with Shannon. The table now read - (1) Ian Dwyer (Bective Rangers and County Carlow) 37 tries, (2) John Lacey 35 and (3) John McWeeney 34.
Lacey went top of the table when he scored eight tries to McWeeney's four during the 2001/02 campaign and still remained there at the end of the 2002/03 season.
On November 15, 2003 at the Belfield Bowl in UCD, Lacey, a Tipperary man, became the first player to accumulate 50 tries in the AIB League. Ian Dwyer, also at UCD later on in March that season, became the second player.
The table at the end of 2003/04 read - (1) John Lacey 55 tries, (2) Ian Dwyer 50, (3) Steven Smyth (City of Derry) 49 and (4) John McWeeney 46.
Lacey, a Munster Development Officer, now returned home to play with Clanwilliam while Dwyer hung up his boots. During Mary's brief sojourn in Division Two (2004/05), McWeeney added six more tries to his tally and at UL Bohs in January of that season, he became the third player to score 50 AIB League tries.
He now lay three tries behind Lacey but could only close the gap to two during the 2005/06 campaign, the season he captained his club on their return to Division One.
A try at Dolphin in December this season, followed by his brace at Castle Avenue a few weeks ago, has moved him ahead of Lacey. Not only is McWeeney presently the all-time top try scorer in the league, but he is also the top try scorer in Division One with 50 touchdowns to his credit.
AIB LEAGUE'S ALL-TIME TOP TRY SCORERS:
1 - John McWeeney 56 tries (all with St. Mary's College)
2 - John Lacey 55 tries (45 with Shannon and 10 with Sunday's Well)
3 - Steven Smyth 52 tries (all with City of Derry)
4 - Ian Dwyer 50 tries (29 with County Carlow and 21 with Bective Rangers)
5 - Brendan Burke 49 tries (all with Barnhall)
(Travelling fast behind the players above is David McKechnie of Greystones who has scored 46 tries over five seasons but none yet in Division One)