Tottenham Hotspur were beaten 2-1 by Newcastle United at White Hart Lane on Sunday.
Spurs were beaten 2-1 by the Magpies at White Hart Lane, after putting in a very poor second-half performance.
Tottenham had taken the lead through Eric Dier, and they looked set to extend their unbeaten run in the Premier League to 15 matches.
However, relegation-threatened Newcastle hit back and scored late goals through Aleksandar Mitrovic and Ayoze Perez, leaving Pochettino frustrated with his side for taking their foot off the gas.
"I think there is an easy explanation – we lost control and we started to make easy mistakes," he said.
"When we needed to play one-touch we were playing three-touch, when we should have been playing forward we dropped.
"These are easy mistakes that gave the opponents belief in the game."
Tottenham have had a tendency to throw away victories in previous seasons, but the strength of their squad has been impressive in the current campaign.
The Lilywhites have been a tough obstacle to overcome this term, but their defeat to Newcastle was frustrating.
Tottenham never played at their best throughout the whole contest, and they were punished for being off their game.
Pochettino’s side would have moved into the top four had they beaten Newcastle, but they remain in fifth place after their defeat.