The striker was dropped to the bench for the match, but scored within two minutes of his arrival in the second-half.
After five games without a goal, it was a welcome return to form for Lambert, who also set up another one of Saints’ strikes.
Pochettino said: “As manager, I’m always looking for what’s best for the team and also what’s best for every single player, to get the best contribution out of every single player.
“I thought Rickie coming on as a sub would be good for him, and it showed, the fact that he scored a goal.
“Sometimes tactical decisions go your way, and it shows that you’ve made a tactical decision that was right for the game, and that was the case.”
Pochettino’s line-up, while retaining the same formation as normal, had a different feel to it, with Jay Rodriguez moving from his position on the left to play the lone striker role, while playmaker Gastón Ramírez was handed a rare start.
“We inserted some variables that we were looking, of course, to favour our attacking intent,” said Pochettino.
“I thought Gastón and Adam associated quite well, so we were just looking for fresh alternatives today. We’re always looking for different tactics that are going to help us out through a long season.”
While Pochettino certainly worked out a system that benefited Saints going forward, he was left frustrated by how slack they were at the back on occasions.
In fact, Saints nearly undid all their own good work during a wild final five minutes, when they conceded twice.
“It’s a great lesson that we have to learn,” he said. “We’re a young side that’s still growing, and the main lesson is that, obviously, the game is not finished until the final whistle has blown.”
Despite that frustration, the result was still a positive one for Saints, moving them up to eighth in the table.
It was also just a second home win in nine league matches.
Pochettino said: “I think it’s vital to get more wins at home and we did just that, and that’s massive and really important for us.
“I think, overall, we’re having a fantastic season, if you analyse just how tough this competition is.
“If you analyse that, you’ll see we’re having a very good season, especially with everything that’s happened at the club.”