The visitors started outstandingly at White Hart Lane on Sunday, moving into an early 2-0 lead thanks to goals from Jay Rodriguez and Adam Lallana.
However, Christian Eriksen struck either side of half-time before Gylfi Sigurdsson’s late thunderbolt ensured the visitors headed back to the south coast empty-handed.
Southampton boss Pochettino believes the defeat was harsh on his side and was left to rue decisions going against them.
"I thought we had a very good game overall," he said. "We were 2-0 up and controlling it, especially in the first half.
"Their first goal came from a clear foul on Dejan Lovren so that should not have been allowed to stand.
"Then came the equaliser, an injury to Nathaniel Clyne as well and it was a heavy punishment for the way that we played today.
"I thought that we deserved more but there were some refereeing decisions that did not go our way today and, despite that, I thought we did very well against a very good Tottenham side/"
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