Liverpool boss Rafael Benitez believes Steven Gerrard is paying the price for his recent outings with England.
Gerrard played in both Euro 2008 qualifying wins over Israel and Russia, despite being a doubt with a broken toe.
And Benitez told the Liverpool Echo today: 'It could be that playing twice for England has had an impact.
'They (England) knew (what I felt about him playing in both games) - but everyone was talking about how important this situation was for England.'
Gerrard came off with cramp after 71 minutes in the win over Israel before playing the full game when Russia lost at Wembley four days later.
Since his return from international duty, the 27-year-old midfielder has seemed to be struggling for top form, while Liverpool have failed to impress in goalless draws against Portsmouth and Birmingham.
Gerrard came on as a substitute in the 0-0 draw at Fratton Park but started last week's 1-1 draw with Porto in the Champions League as well as Saturday's Anfield clash against Birmingham.
Benitez added: 'His national team is England but it is clear that these players cannot play every game for 90 minutes.
'Gerrard was not 100% physically fresh, I don't mean fit but fresh.
'In these kind of games you need to keep the tempo really high and if you play too many games in a row for 90 minutes, especially if you are not fit then normally you have problems.'