Lamela opened scoring for Tottenham in the 33rd minute but goals from Odegaard in the 44th and Alexander Lacazette’s 64th spot-kick ensured victory for Mikel Arteta men.
The results leave Spurs dream of finishing in the Premier League top four hanging in the balance.
Spurs were later reduced to ten men in the 70th minute when Lamela was sent off but Mourinho believes his team’s performance in the last 20 minutes should have given them a least a point from the Emirates Stadium.
He, however, blamed the team’s first-half performance, saying, “The first half, probably… I don’t remember a worse performance than in the first half.
“I have to try to take my memory back, maybe the first half at Sheffield United before lockdown. I don’t remember such a bad first half as we had, but the result was 1-1. The game was not lost, it was open,” the Portuguese told Spurs TV.
“We improved immediately in the second half. But even with 10 players and losing 2-1, then we were a team, then we played with intensity and with great desire and we deserved that point for what we did in the last 20 minutes playing with one player less and with the chances we created.”