The Saints striker has been in the England squad all season and could win his fifth cap tomorrow, in the friendly against Denmark.
However, Lambert knows he is still not established enough to be certain of earning a dream ticket to Brazil this summer.
“Obviously, I still understand it’s nowhere near secured,” he said.
“I’ve got two months to try and prove my place, and it’s as simple as that.
“I’ve always said if I don’t make it I’m going to be grateful that I got my chance, and that’s still the case now.
“I’m obviously desperate to go, and now I’ve got two months to prove that I’m good enough to go, so that’s all I’m trying to focus on.”
Tomorrow night’s encounter at Wembley represents England’s final match before the squad for the World Cup is announced, on May 13.
Lambert’s main rival for a place has always looked like being West Ham’s Andy Carroll.
Having hardly played all season, he was not chosen by Hodgson for this week’s game, but the England boss did insist the door was still open for him.
If it is indeed a straight shootout between the two of them, though, then it appears to be Lambert’s place to lose.
But the Saints striker feels it is vital he impresses Hodgson in person this week.
“Obviously, I understand that I’ve got to do well,” he said.
“I’ve got to do well in every training session, any minutes I get. I understand that – it’s fine.
“I relish that, to be honest, and that’s what I’ll be looking forward to.
“It’s going to be great, it’s going to be enjoyable. I’m just gutted that we’re going into it after a defeat like that (against Liverpool).”
The latter is in line for his debut, and Lambert could not be happier for the 18-year-old left-back, who is 14 years his junior.
“I’m made up, I’m absolutely over the moon, for the club, and for Luke especially,” he said.
“I think he’s had a terrific season and it’s fully deserved.
“I think throughout the game (against Liverpool) he looked strong. First half he was putting in some great balls and we should have done better with them.
“Whoever he’s playing against, whether it’s the best right-back in the world, or the best right winger, he’ll play his own game and he’s confident that he can compete against the best, and (his display against Liverpool) just goes to show again that he can.”
Lambert certainly has no fear of Shaw being overawed if he is handed his first cap tomorrow.
“Absolutely not,” he said. “I think his mental strength is one of his main strengths.
“The way he’s handled coming into Southampton, it hasn’t bothered him whatsoever. It’s frightening.
“Not just him, but all of the kids at Southampton. The way they’re prepared, it’s in them now. It’s full credit to them and the club.”
Lambert knows what it feels like to be venturing into the England camp for the first time, and he says he will be on hand to issue any advice if needed.
“Obviously, it’s nerve-racking, it’s overwhelming. You have to try and get your nerves in check, because, obviously, the only importance is the game and doing well,” he said.
“It is hard at first, but I’ll be here to help the lads, Jay and Adz and Luke, but I’m sure they’ll be fine.”