Arthur Papas believes his Newcastle Jets side felt the effects of playing three games in nine days as they slipped to a 4-2 defeat against Melbourne City.
The Jets are aiming to finish in the top six of the A-League this season but have work to do after picking up just two wins so far to leave them in 10th place on the ladder.
The Jets went over a month without playing an A-League fixture following a number of postponements and since returning to action have been playing catch-up.
Papas felt that was evident during the game against City when they found themselves 3-0 down soon after half-time, before managing to fight back and make a game of it.
The games will keep on coming as they face Melbourne Victory on Saturday and Papas has admitted he will have to freshen up his starting eleven for the clash.
He could also be without his captain and key defender Matt Jurman who picked up an ankle injury on Tuesday night and faces a race to be fit.
"I felt for the first time that we just weren't close enough physically and that's a concern obviously," Papas told reporters after the game.
"In fairness, we're talking about a team that didn't play for 42 days and goes and plays three games in nine days, so you would expect that to happen. That's why we've got to look at the squad and see what changes we can make now."
Papas did have plenty of praise for the opposition though and still believes the reigning premiers are the best side in the A-League.
"I know it's easy to get caught up in ladders, but if you look at their game over time and you see the way they are playing, they are still the benchmark for me," he added.