Spurs hopes of securing a Champions League place suffered a blow at The Stadium of Light as Darren Bent came back to haunt his former club in a 3-1 win for Sunderland.
Bent fired in a first-half double - the opener coming after just 36 seconds for the fastest goal in the Premier League this season.
But the former Spurs striker could possibly have had four if he hadn't been denied twice by Spurs keeper Heurelho Gomes from the penalty spot.
Bent did beat Gomez from the spot for his second but, when referee Lee Mason awarded two further penalties, the keeper was up to the test, pulling off two great saves to deny his former team-mate.
"From the neutral's point of view, it was probably a great game," Redknapp said after the game.
"Sunderland were up for it today - they don't play like that every week, do they?
"But today, they were full of it. They chased every ball, they pressed, they worked and they played very well today.
"We had a couple of chances in the first half and couldn't stick one away so we had to go for it because at half-time we were 2-0 down.
"So, I played with two up front and pushed Eidur Gudjohnsen in behind and played with two attacking midfield players and two full-backs who I told to just bomb on at every opportunity.
"We were always going to be open to getting caught on the counter-attack, but that was a chance we had to take - when you're 2-0 down you have to go for it.
"At 2-1 we were back in the game but then they had an amazing finish from Zenden, it was one of the all-time great volleys.
"We've got to pick ourselves up and get going again next week.
"We've got a tough run-in but if we can get one or two back to full fitness then we've got some great games to look forward to."