12 Dec, 14:42
Prop Cian Healy is expected to miss the start of the 2014 RBS 6 Nations after undergoing surgery on his injured ankle on Wednesday.
A Killian Lett-inspired try saw UCD shoot into an early lead at Belfield and they were still 8-5 to the good at half-time.
Bohs hit back when Cathal Sheridan made a break before passing for Harry De Stacpoole to touch down in the right corner.
A late first half penalty kept the hosts ahead but UL, captained by Eddie Rossiter, used a second half wind advantage to forage ahead.
Peter Boland claimed a try which Daragh Frawley converted, and after a period of UCD attacking Frawley tagged on a penalty for a 15-8 lead.
A further Frawley penalty left UCD's hopes hanging by a thread and when De Stacpoole pulled off an interception and gleefully dived over for his second try, it was game over.
Frawley's conversion from in front of the posts completed the scoring at 25-8. Speaking afterwards, UL Bohs head coach Noel Davis singled out Munster Under-20 player Ian Cross for his excellent performance at centre.
In the other semi-final at Stradbrook, hosts Blackrock College emerged victorious over Lansdowne on a 10-8 scoreline.
Lansdowne looked on course to set up a repeat of last year's final when they led 8-7 heading into the closing stages.
But Ireland Under-20 starlet Ian Madigan stepped up to land a late penalty and send a never-say-die 'Rock side through.
Madigan had earlier converted a try from Robert Johnson, the former Ireland Under-18 Schools winger, which delighted the big home crowd.
So all roads lead to Tullamore this Saturday for the final of what has been another action-packed All-Ireland Under-20 Cup competition. Two 10-minute periods of extra-time will be played if the sides are level at the end of normal time.
A second half try from Dave Moloney gave UL Bohs a gritty 5-0 win against Lansdowne in last year's decider in Portlaoise. Read the report here.
2008/09 ALL-IRELAND UNDER-20 CUP FINAL: Saturday, April 11
Blackrock College v UL Bohemians, Spollanstown, Tullamore RFC, 2.30pm