Tigers, with one home defeat since October, edged in front around the hour mark and ended the game strongly to take the four points in Round 12 of the Gallagher Premiership campaign.
Telusa Veainu had a score disallowed in the game’s opening attack and it was Warriors who got in front until Olowofela’s intervention just after the half-hour.
After reaching the break level at 8-8, McPhillips added the only points in the second half on a blustery and bitterly cold afternoon as Tigers ended a five-match winning run by the Warriors in this encounter.
Noel Reid got the game underway, kicking towards the Mattioli Woods Stand and with the wind at Tigers’ backs, and just 76 seconds had elapsed when Telusa Veainu picked off a pass from Ollie Lawrence on halfway and ran clear to dot down behind the posts.
But referee Adam Leal called for a knock-on by George Worth ahead of the intercept and brought play back for a Warriors scrum which ended in a penalty against Tigers.
The whistle blew again for a tackle off the ball after the lineout and Duncan Weir turned down a kick at goal into the wind to keep play in the corner. Tigers resisted the forward drive for the line but Warriors had another lineout five metres out and then another penalty.
This time Warriors lost ball forward and, although Lawrence dived over the tryline, play came back for a defensive scrum.
Tigers had spent almost all of the opening 10 minutes inside their own 22, but had brief respite from an unusual source when referee Leal collided with Warriors full-back Jamie Shillcock in midfield. As the game waited to restart with a scrum, Noel Reid left the field, to be replaced by Johnny McPhillips.
Warriors retained ball and, after Veainu had stopped a charge from Ted Hill, they recycled and Perry Humphreys found space to run in and score to the left of the posts. Weir was unable to add the extras with his team five points in front on 13 minutes.
A quick throw between Jonah Holmes and Veainu finally gave Tigers some promising ball in the opposite half of the field where Warriors were penalised three times in quick succession. At the third call, McPhillips asked for the tee and kicked his first Premiership points to make it 3-5 on 24 minutes.
Another 10 minutes elapsed before Olowofela’s try, winning the foot-race to a superb kick down the line by White after picking up loose ball on the back of a Warriors ruck. McPhillips was just wide with the conversion kick but Tigers were 8-5 in front with five minutes of the opening half to play.
But Weir had the last word, levelling the scores just before the break with another penalty, though Tigers had Veainu to thank for hauling down an incisive break from Lawrence just short of the tryline.
Some strong work in possession and composure to recycle ball gave Tigers some good momentum in attack, with Dan Cole’s carry gaining territory almost up to the tryline before he was closed out. Nephi Leatigaga joined the Tigers front row as play came back for a Warriors knock-on in the contact and the scrum brought a penalty which McPhillips kicked for an 11-8 lead.
Joe Thomas joined the backline for his Premiership debut on 68 minutes and Harry Wells took on the captaincy when Cole was replaced in the closing 10 minutes.
Two big set-piece drives got Tigers going forward again and a clever kick from White had Warriors scrambling back ahead of Jonah Holmes with the clock ticking down towards the closing five minutes.
Leatigaga was at the centre of the work as Tigers kept Warriors pinned back on their own line, until Veainu spun a long pass out to Olowofela on the left. He reached out to the line but, after repeated looks from TMO and referee, there was no conclusive proof of a touchdown.
Play, though, did come back for a penalty in front of the posts. With the home crowd in good voice, the call was for a scrum and another whistle followed with a minute remaining on the clock.
McPhillips made the kick for a 14-8 lead, though he had already been told the game would restart and Tigers managed to reclaim ball to close out an important victory.