The Saints forward, left, agreed that it was “probably” a battle between himself and West Ham’s Andy Carroll for a place in Roy Hodgson’s squad this summer.
And, with less than four weeks until the England manager names his players for Brazil, the likelihood is that most spots will have already been pencilled in.
But Lambert thinks the last four matches of the campaign might still have a bearing on Hodgson’s decisions.
“I think they will matter,” he said. “I think he’s obviously watching everyone, so it’s going to be hard decisions and that’s good.
“Obviously, he wants hard decisions, and he’s going to have a few.
“I understand I might be one of those situations, so I’ve just got to try and do well now, and score some goals in the remaining four games.”
Lambert has 11 Premier League goals this season, but has been at least partly responsible for 21 in total, having added ten assists.
He believes, therefore, that he has built a good case.
“I’m very happy,” he said. “I always want to do better, but what I’ve done, I think, is given my all.
“I could have scored more goals, I always think that, but I’ve done as good as I could, I’ve given everything. I’ve got no complaints myself.”
As for his current form, Lambert added: “I’m playing well at the minute, I’m feeling good, and we’ve won a lot of games, so it’s going well.
“Obviously, we lost against Cardiff, which was a bit of a weird game, but full credit to Cardiff and we go into a game Saturday where we’re confident that we can take three points.
“If I can get a goal or I can help then, obviously, the better for me, but I’m obviously focused on getting three points first and foremost.”
In fact, Lambert insists that, most of the time, he blocks out thoughts of the World Cup.
“I don’t think about it too much,” he said. “I do think about it, but it’s not like keeping me up at night or anything like that.
“If it’s going to happen it’s going to happen.
“I already understand there’s a big possibility that it might not happen.
“That’s not to say that I’m not desperate to go, but, like I said, if it’s going to happen it’s going to happen.”
The 32-year-old says he doesn’t want to be picked on the basis of his renowned penalty skills – he has scored a perfect 34 out of 34 for Saints – but he does hope that the number of goals he has laid on this season is something that will benefit his chances, even if he admits he perhaps should have pulled the trigger himself on some of those occasions.
“I would hope so,” he said. “I do try and see the best situation, whether that’s me to shoot or someone else.
“I think I’ve always had it, (but) I think it’s come more in my game this year.
“Whether that’s a good thing or a bad thing I’m not too sure. I think I should have shot a bit more than I should have passed it really, but it’s not a bad thing to have I would hope.”