Fabio Capello believes it could be a 'dangerous' time for Barcelona as they face a gruelling run-in.
Barca have been scintillating at times this season but their lead at the top of the Primera Liga title has been cut to just four points.
Whereas Capello's former club Real Madrid have no other distractions, Barcelona are still hoping to be crowned as European champions.
They travel to England next Wednesday to face Chelsea in the second leg of their UEFA Champions League semi-final, while Pep Guardiola must also prepare for the Copa del Rey final against Athletic Bilbao in a fortnight's time.
And Capello thinks tiredness could be a factor as Barcelona challenge for silverware on so many fronts.
"There are too many finals and semi-finals. This is dangerous for a team," the England boss told Marca.
"Although everyone says Barca have a squad of twenty-something players, the truth is there are very few who can really make a difference."
Barcelona defender Rafael Marquez, meanwhile, is to undergo surgery to repair an injured left knee.
The Mexican had already been ruled out for the rest of the season after picking up the problem against Chelsea on Tuesday.
Further tests have now been carried out and he will be sent for his operation on Saturday.