Lambert said: "It's a unique thing for a guy to stay at a club for any length of time. The likes of (Paolo) Maldini , (Steven) Gerrard and Ryan Giggs have all done it, but there's not many who stay as long as Gabby and he's only in his mid-20s. He's still got a lot of football left in him, a lot of time to do well.
"I think he's on the top of his game right now. His goalscoring at the minute is excellent at the minute and he's now equalled Dwight Yorke's tally and given time he'll surpass it. I think he enjoys the role he's playing and it shows in the way he's playing.
"People tell me he's playing his best for two or three seasons but I don't know because I wasn't a part of years gone by but for this season he's certainly been playing really well for us. When we started pre-season he was looking really good and then he hurt his knee and we lost him for the opening spell.
"At the minute his work rate is extremely high and he's creating things and scoring goals and that's a great thing.
"We try to concentrate on his strengths rather than concentrate on negatives. When he goes on a run you won't catch him, you'd need to be the road runner to do it.
"When you have a player with pace coming at you time and time again you know you're in for a hard day. When he gets it and he's on a run, we ask him to make something happen, whether it be take someone on or have a shot at goal. I think it's important to concentrate on his strengths."