Andrew Waterworth admits Linfield have no margin for error in the title race.
The striker scored a 76th minute winner at Mourneview Park to keep the Blues within sight of leaders Crusaders.
But with the seven-point gap showing little sign of narrowing, Waterworth believes even one defeat could be catastrophic.
He felt Saturday's win was another crucial result.
"It keeps us on the coat tails of Crusaders," he said.
"I think over the past three years with us, every game at this stage of the season has been like a cup final.
"We've had pressure because we can't afford to lose. If we lose it really is goodnight."
Waterworth's strike was his 14th of the season.
He met a cross with a first-time left foot finish which seemed to take a touch off Glenavon defender Kris Lindsay.
The Blues had led at the break through Aaron Burns' stylish opener.
He collected a flick on from Waterworth and darted past Caolan Marron before netting with a thumping left-foot strike.
Glenavon stepped it up after half-time and levelled in the 64th minute.
Mark Stafford dived in to block a cross from Andy McGrory, but the ball struck his arm, resulting in a penalty.
McGrory converted from the spot to level it up at 1-1.
But the momentum swung back to Linfield after Ciaran Martyn collected a second booking, leaving the home side down to 10 men.
And Waterworth netted with 14 minutes remaining to secure a vital three points.
He added: "I did think we would score. It was a good result, Glenavon are a good side, and that pitch is like quicksand so it was a really tough game.
"But I felt confident, without disrespects to Glenavon, that we would get one."
Linfield have lost just once since mid-November - a 1-0 home defeat to Coleraine on January 3.
Waterworth feels they are building momentum going into the closing months.
And he believes they need to keep following Crusaders' example by digging out narrow wins.
"I think we've had momentum. I think Coleraine was a one-off, a slip-up," he added. I alluded to it a couple of weeks ago - we were tired, we were playing with nine or 10 men for about a month there.
"The Coleraine game was a slip-up but we've been playing well and there's a good atmosphere and a good team spirit."
For Glenavon it was another frustrating result, although Dungannon's loss at Ballymena meant they stay in sixth.
Boss Gary Hamilton will be aiming to get back on track against Ballinamallard in a rearranged game on Tuesday night.
He was unhappy with the second yellow card for Martyn, awarded for a late challenge on Ross Gaynor. "I thought the referee had a really good game today, but with that one I just didn't see where it was coming from," Hamilton said.
He added: "It ruined the game for us, it probably didn't ruin it for Linfield because they go on and get the winner.
"But even with 10 men I thought we did well and fought hard, and we certainly aren't ashamed of our performance."
GLENAVON: Tuffey, Neill (Kilmartin, 54 mins), Canning (Gray, 80 mins), Lindsay, Patton, Marron, Martyn, Sykes, Bates (Kelly, 73 mins), McGrory, Moorhouse. Unused subs: Hamilton, O'Mahony
LINFIELD: Carroll, Haughey, Stafford, Callacher, Lowry, Ward, Clarke, Gaynor, Millar (Stewart, 75 mins) , Burns, Waterworth. Unused subs: Casement, Fallon, Amuneke, Carson
Referee: Steven Taylor (Belfast)
Results: Ballymena United 3 Dungannon Swifts 2; Cliftonville 2 Ards 1; Coleraine 4 Portadown 2; Glenavon 1 Linfield 2; Glentoran 0 Crusaders 3; Carrick Rangers 1 Ballinamallard United 2 (Friday) Fixtures to come Tomorrow (7.45pm): Ballinamallard United v Glenavon; Friday (7.45pm): Ards v Glentoran; Saturday (3pm): Ballinamallard United v Coleraine, Carrick Rangers v Dungannon Swifts, Crusaders v Cliftonville, Linfield v Ballymena United, Portadown v Glenavon