Jonathan de Guzman's 25th minute goal, which came from a fine Leon Britton pass, had the Swans ahead but a red card to Chico Flores and subsequent questionable penalty to Glenn Murray got the Eagles back into the contest.
The draw came just days after the Swans played impressively only to be beaten 3-1 in Italy by Napoli in the Europa League which had Monk defending the Premier League output of his players.
"I knew it was going to be tough for the boys second half, with the energy levels," Monk told Sky Sports.
"There was the early substitutions as well where the boys were fatiguing. I knew that was going to come and second half it was going to be hard for us.
"But I thought, after the sending-off as well, we dug in real deep and that's all you can ask from the boys.
"Okay, we didn't pass the ball as well as we could have second half but I think that was more down to us in terms of probably fatigue levels, because of the weeks that we've just had.
"But next best thing is if you can't win a game, make sure you don't lose it and they did that today."
The draw made it one win in five Premier League outings for the Swans who find themselves sitting 14th on the table, five points above the relegation zone.
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