The talented centre-cum-winger, who only turned 19 in April, went close to making it two tries on the trot in Tuesday's 17-0 loss to defending champions New Zealand.
Spence was literally inches away from registering Ireland's first points against the Baby Blacks, going close on two occasions in the second half.
Unfortunately further disappointment followed after the match when it was confirmed that he had suffered a sever wrist sprain.
While it was initially thought he may have fractured his wrist, the Ireland camp confirmed that it was a very bad sprain and that Spence will have further X-rays and treatment to rehab the injury.
The Ireland Under-20 management have called up Danny Barnes as Spence's replacement.
Tralee youngster Barnes, a noted outside centre, plays his club rugby for UCC and has featured for the Munster Under-20s this season.
He partnered current Under-20 Eamonn Sheridan at centre in the Ireland Under-18 Clubs side that finished as runners-up at the 2007 European Championships.
Both Spence and Barnes played for their respective clubs, 'Hinch and UCC, in last month's AIB League Division Two play-off final at Dooradoyle.
The Ireland Under-20s will finish off their Pool A campaign with a game against tournament newcomers Uruguay at Mizuho Rugby Ground on Saturday (kick-off 1pm local time/5am Irish time), with the play-offs to follow next week.