First-half goals from Demba Ba and Eden Hazard put the home side in control before the break but substitute Rickie Lambert pulled one back for Nigel Adkins men in the 58th minute.
Jason Puncheon then snatched an equaliser 15 minutes from time to ensure Chelsea’s poor home record under Benítez continued.
The west Londoners have won just once in six games at Stamford Bridge since the Spaniard took over from Roberto Di Matteo back in November.
“We have to be more clinical when we have chances,” said the Chelsea boss after the draw, which leaves them six points behind second-placed Manchester City.
“We have to manage the game, score the third goal and finish the game but we did not do it. We had a lot of chances again, even at 2-0 up, but we did not take them.”
Benítez refused to rule the Blues out of the Premier League title race despite the 13-point gap to leaders Manchester United.
He added: “We are in the top three so we will try to be as high as possible, then try to think about the next game.
“We think about the next game, and the next three points and that is it.”
Meanwhile, Saints boss Adkins was delighted that his tactical approach paid dividends as his side moved up to 15th place in the table.
“We came with a game-plan,” he said. “Chelsea are a good side and we came to block them, deny them space and counter-attack.
“To go two goals down, when we could have cleared both, was a blow but we showed great character in the second half – great credit to my players.”
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