Rodriguez damaged knee ligaments in Southampton's 4-1 league defeat at Manchester City on April 5 and will not be fit until next season.
Lambert knows he must impress in Southampton's final four Barclays Premier League games of the campaign to stand any chance of edging West Ham rival Carroll out of the England squad.
"It's four games to try and impress; it's four games to try and score goals," said Lambert, admitting Carroll is "probably" his direct rival for World Cup selection.
"I think I was vying for the central position, I think Jay might have been vying for one of the wide ones. If you're asking for my opinion, that's what I think was happening.
"Jay's definitely not forgotten by the Southampton lads. We see him every day, it's obviously a hard thing to accept mentally what happened, it's going to be hard, but he will be back, he'll be back next season and he'll be back stronger mentally.
"He'll be back scoring goals not too long away, so that's all he's focused on, and we don't treat him any differently.
"The timing of it is the cruel thing, but you've just got to get on with it, but, like I said, he'll be back next year stronger."
Southampton take on Aston Villa at Villa Park on Saturday aiming to hit back to winning form after last weekend's frustrating 1-0 home loss to Cardiff.
Well aware of the watchful gaze of England coaches Hodgson and Ray Lewington, Lambert said he must set all World Cup thoughts aside in favour of fighting for form and goals with Saints.
"Most importantly, we've got four games to try and get more points for Southampton and try and push us up further in the league," said the 32-year-old target man.
"We got asked the same question a few games ago - 'we've got nothing to play for' - but then we won three out of four games, so the lads are still very hungry and very determined to do well and that's what we'll be trying to do in the remaining four games.
"I think we've had either Ray or Roy watching our games for the last ten games I think, so we know we are getting watched and that's brilliant for them to be watching Southampton.
"I try not to focus on it, if I'm being honest. I try to play my own game, I think that's the best way to go about it.
"I think you can't think too much about it, because I think it might affect your game.
"You've just got to get on with it, try and do well for Southampton and hopefully Roy or Ray are impressed, that's it really."
- Sports & Recreation
- Roy Hodgson
- Jay Rodriguez