Manchester United manager Louis van Gaal says his team "struggled for life" in the second half of their goalless draw against Tottenham.
Victory would have enabled third-placed United to close the gap on Chelsea and Manchester City, with the top two also dropping points on Sunday.
Van Gaal blamed the physical demands of the festive schedule for the stalemate.
"It is scientifically proven that the body cannot recover within 48 hours," the Dutchman said.
United, who beat Newcastle in a 3-1 home win on Boxing Day, are 10 points behind leaders Chelsea going into the new year.
The visitors created several good chances in the first half at White Hart Lane, with Juan Mata's deflected free-kick hitting the post.
Despite criticising England's busy Christmas schedule, Van Gaal named an unchanged United starting XI for the first time in 85 Premier League games.
On "losing two points"
"We had our best performance this season in the first half, we could have scored four or five goals.
"But when you play the best half of the season as we did, when you create six or eight chances, then you have to finish those. But when you don't reward yourself then normally the opponents win.
"Even when we were on the goalline we couldn't score but the first half was a fantastic half of ours. I was very happy.
"You need also a little fortune. Tottenham could score also in the second half. I'm happy that they didn't."
On England's busy Christmas schedule
"You could see the difference in the second half, we struggled for life. We played within 48 hours and bodies were tired. We do not have the fittest players in the world.
"When the FA allow that, to play so many matches, you see what it's like.
"The second half was much different from the first half. And not only for Manchester United, also for Tottenham Hotspur.
"I think Tottenham Hotspur can play much better than today. Also my team could've played in the second half much better. You cannot do that."
On his team's title chances
"When you can't win these types of matches when you're the better team, like we haven't against Aston Villa and Tottenham, it is very difficult to be champions at the end of the season.
"But I still think we can become champions because we are continuing to improve every week."
On United's injury problems
"The players were tired. We don't have the fittest players in the world.
"Players like Luke Shaw and Chris Smalling are coming back from injury. You cannot play 90 minutes. Maybe you can play 20 minutes.
"We had to put players on the bench who are coming back from injury. I took a risk already with these kind of players by putting them on the bench.
"That's why I could not change."