Andros Townsend, the recent hero of England's World Cup qualification, shone again with an inspirational goalscoring performance and opened the scoring - albeit with a cross-cum-shot - in the 31st minute.
Spurs completed victory with a second goal from Roberto Soldado in the 69th minute, but Lambert focussed on the positive of seeing Christian Benteke back in action as a second-half substitute following his injury lay-off.
The Belgium international headed a chance over just before Tottenham grabbed the second, and Lambert felt that was the turning point.
"I didn't think there was too much in the game," Lambert told Sky Sports. "The first half was pretty tight.
"In the second half we started well and looked as if we might get the goal as well with Christian's header. If that was a goal...we were on top at the time.
"You never feel comfortable in the technical area, but we had been playing well and with confidence. You can't fault our lads for their effort and on another day we might have got something.
"Since the start of the season there has been progress. If we play like that we'll win more games than not."