Linfield manager David Healy says his side "shot ourselves in the foot" as Glenavon scored a 96th minute equaliser to deny the Blues top spot in the Irish Premiership table.
Aaron Prendergast tapped home for Glenavon after Darragh McBrien restored Linfield's lead in the 88th minute.
Healy's side are now one point behind reigning champions Larne.
"It's disappointing, especially in the manner," said Healy, who described his side as "average" in the 2-2 draw.
After holding an advantage over Larne at the top of the table in the new year, Linfield have lost to Dungannon Swifts and drawn with Glenavon to hand their title rivals an advantage with 10 games to play.
At Mourneview Park, Stephen Fallon gave Linfield an early lead but the Lurgan Blues hit back through James Doona.
McBrien looked to have put Linfield in a strong position but Prendergast reacted quickest to equalise after Peter Campbell's 96th-minute effort came back off the post.
"I thought we had done enough when we scored to go on and win it," Healy added.
"I thought our performance today was average. We found a way to get ahead in the game and great credit to the players, but again we shot ourselves in the foot. We didn't do the basics in the last 60 seconds of the game and we got punished.
"[It's disappointing] Especially so late in the game. We altered the shape a little bit, we got ourselves in front and we didn't manage the rest of the game, so yeah, it's disappointing.
"Great credit to Glenavon, they put it up to us."
In contrast to Healy, Glenavon manager Stephen McDonnell was delighted with the response of his side against the title challengers.
"I think it was thoroughly deserved over the 90 minutes," McDonnell said.
"I thought it was a fairly balanced game, in terms of both teams went for it.
"Obviously happy with the outcome, when you are in a losing position to have the character to come back for the second time in the game against an opposition as superior and ruthless as Linfield are.
"I feel it was a big mental moment for our group.
"When you concede so late in the day it is a bit of a sucker punch after the amount of effort we put in. We were probably scratching our heads wondering where we were going to score from.
"We managed to get a bit of quality in the dying moments. We're delighted with the result."