The Brazilian has been a regular fixture in the Reds’ starting line-up this season, with Jurgen Klopp preferring to play Firmino up front ahead of the likes of Daniel Sturridge.
Firmino has scored eight goals and made three assists in 23 Premier League games for Liverpool so far this season.
However, McAteer believes that Firmino has been struggling to maintain his performances in recent weeks due to Liverpool’s demanding style of play.
McAteer told 888Sport: “Liverpool’s game is all about high-pressing in the final third so Firmino does a lot of running – which is why he gets in ahead of Daniel Sturridge who wants to be more static and play with his back to goal – and he has become a victim of not having a Christmas break.
“He’s struggled with that and I was really surprised when Klopp made all his changed for Wolves yet Firmino played.
“So I am worried about his fitness.”
Liverpool head into their clash with Tottenham desperately looking to return to winning ways after the disappointment of their 2-0 loss to Hull last weekend.
The Reds, who finished eighth under Klopp last season, are yet to win a Premier League game in 2017 and are currently 14 points behind leaders Chelsea, in fifth place in the top-flight table.
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