Inter Milan boss Walter Mazzarri was left disappointed with defeat to Eintracht Frankfurt.
Inter lost 3-1 to the Germans yesterday.
"Was this down to the heavy workload during the week? I don't want any excuses," Mazzarri told Inter Channel.
"My fitness coach told me we needed to work on strength right now, as otherwise we'd lack sharpness later on in the season. I think the lads paid that price and they looked pretty heavy-legged.
"We weren't sharp and I hope that is only down to the fitness work. At this stage of the season it's easy to do well in one game and badly the next. If you lack just a tiny bit of sharpness and focus, then you can trip up.
"Up until our goal Eintracht hadn't created any chances, but we have to be more concentrated in some situations. Perhaps we subconsciously let go after taking the lead.
"In the second half we focused on damage limitation."
