Harlequins boss Paul Gustard was 'gutted' after his side suffered late heartache at the hands of a Saints side he labelled 'cynical'.
Alex Mitchell's last-minute try and James Grayson's nerveless conversion handed Saints a crucial 20-19 Gallagher Premiership win at the Stoop on Saturday afternoon.
It cut the gap to fourth-placed Quins to just four points with three games of the regular season to go.
And Gustard, who has now seen his side lose four successive league matches, was far from happy after the game.
"I'm obviously gutted because we had the game under control," Gustard said.
"We fought our way back into it because our game management from 10 minutes to 40 minutes wasn't good enough.
"We gave them field position and it was our errors - we lost the breakdown, lost aerial contests had a set piece that went awry on two occasions and gift-wrapped them points in the first half.
"Second half, we were much better, we defended exceptionally well, our set piece was good, they were a little bit cynical when we had linebreaks, got into their 22 and they managed to cheat and hold us and not let us get that second score that would have made a big difference.
"But then we were still leading by six points with two minutes on the clock and to lose the game from there is hard to take."
Gustard was impressed with some aspects of Saints' style.
He added: "I thought Dan Biggar controlled the field very well.
"They obviously came here with a plan to play structured in the first 30 minutes, they kicked the ball off the field and they wanted to attack our lineout.
"They wanted to play a territory-based game, the wind was swirling around a little bit and we kept running and running and running inside our own half to put ourselves under pressure.
"We got turned over twice at the breakdown and we got things wrong.
"We were exceptional from the restart in the second half and got ourselves into a commanding lead so to lose it is tough to take."
Quins must now regroup ahead of a trip to table-topping Exeter Chiefs, who lost at home to Wasps this afternoon, on April 27.
Gustard's men will host Leicester Tigers on the following weekend before finishing their season at fifth-placed Wasps.
"We're actually in fourth and with three games left, destiny is in our hands," Gustard said.
"We've got to pick ourselves up because we've lost four league games on the spin for different reasons.
"We were inept against Gloucester, against Saracens we were good for 40 and poor for 40, and we went up to Sale and I thought we were the better team, just ill-disciplined and gave them the points.
"Then on Saturday, we should have closed the game out and didn't. Hopefully it won't cost us."
Harlequins will have to do without wings Nathan Earle and Cadan Murley in the coming weeks as both players suffered horror injuries against Saints.
"It looks like Cadan has dislocated his elbow and Nathan's got a bad knee injury unfortunately," Gustard said.
"We'll find out the full extent over the next couple of days but our thoughts are with them for a speedy recovery."