Russell Martin admits elements of Swansea City's performance against Stoke City were "unacceptable" as they were beaten 3-0 by the Potters.
The Swans were lacklustre throughout the contest at the bet365 Stadium and conceded three second-half goals as Ryan Bennett was sent off.
And head coach Martin said the poor condition of several of his players proved costly as the Swans were beaten for the third time in four matches.
"Not good enough really. We didn't start the game well. Saturday, emotionally and physically, it's taken a lot out of the guys," he said.
"I am angry with the way we started the game, there was nowhere near enough courage or intensity.
"We haven't got enough players like Grimesy, Flynn [Downes], Ben Cabango who can just play relentlessly through a busy schedule.
"We've got guys who are playing catch-up. Hannes [Wolf] and Cyrus [Christie] looked really tired, Oli [Olivier Ntcham] he's not had a run of games. Pato [Jamie Paterson] couldn't play. Ryan Manning was suspended. Naughts [Kyle Naughton] was out. So a lot of changes, and we've paid the price tonight.
"There wasn't enough intensity. We go into half-time at 0-0 and think we have a chance. But a lack of quality and intensity, especially on the ball. It really hurt us.
"The second half we started so poorly, it's unacceptable. We try and make another couple of changes, Benno gets sent off and that's the game done and it's damage limitation after that point.
"Even when we did play around them, it was just so loose and it's cost us tonight."
Swansea's squad remains worryingly thin in areas, with Kyle Naughton and Nathanael Ogbeta both injured while Bennett will now serve a suspension.
Martin has hinted of late that he is attempting to build for next season after admitting there would always be ups and downs during his debut campaign in south Wales.
And the 36-year-old boldly stated that his side will be far better physically next term.
"This team is going to look physically different next season, the physical profile of our players. Tonight was too much for us," he stated.
Swansea return to action against Bristol City on Sunday afternoon.
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