Worcester Warriors boss Alan Solomons says his side let themselves down in the second half at Saints.
The Warriors were 9-6 up at half-time thanks to three Duncan Weir penalties.
But Saints came out firing after the interval, scoring five tries as they eventually cruised to a 35-16 Gallagher Premiership success at a rain-soaked Franklin's Gardens.
George Furbank grabbed two scores, with Tom Collins, Taqele Naiyaravoro and replacement Ollie Sleightholme also dotting down.
And Solomons said: "I felt like we were still in the game (at 20-9 down).
“It was the last 10 minutes of the game when they scored three tries.
“That skewed the scoreline completely.
“Yes, we made the errors and gave them the penalties to get the two tries but to allow them to score three tries in about six minutes was not good.
“The big thing for me was getting a good start and we certainly did that.
“The opening half was good, but we just let ourselves down (in that second half).
“It’s little things that turn a rugby game.”
“What we have got to understand at this level is that you get punished for errors and lack of discipline.
“You go back to those two tries that they got straight after half-time as they came through our mistakes as well as two of the three tries between the 70th and 76th minute.”
Solomons was disappointed with two errors in particular as his side suffered their first defeat of the league season.
“The defences were on top (at half-time), it was a tight game and we were controlling the territory,” Solomons said.
“I felt that we had the edge in the game and I think the momentum swung with the two tries they got between 46th and 54th minute.
“They came off the back of errors and penalties on our part. Then it stuck at 20-9 so you are still in with a shout at that point.
“But at the 70th minute they got a try and then another.
“For one of the tries they counter-rucked at the breakdown, Jono Lance’s kick was charged down and they scored from it.
“The other came from a kick-off which landed short, straight into the lock’s hands and he goes straight through.”