An 89th-minute strike from substitute Son Heung-min secured Tottenham a dramatic 2-1 win over 10-man Watford at Vicarage Road.
The South Korea international pounced to net his second Premier League goal one minute from time and punish the hosts, who had Nathan Ake sent off for catching Erik Lamela with a high leg with the scores level just after the hour.
Tottenham took an early lead when Lamela capitalised on an error from Craig Cathcart to convert inside 11 minutes.
However, Odion Ighalo pulled his side level shortly before half-time with his 30th league goal of 2015 - more than any other player in England's top four tiers.
Mauricio Pochettino's Tottenham had laboured for long periods, but were boosted when Ake - back in the side after sitting out the Boxing Day game against parent club Chelsea - was shown a red card in the second half.
The visitors dominated possession in the latter stages and finally broke through when Song flicked a clever finish with his trailing leg beyond Heurelho Gomes to help Spurs leapfrog Manchester City into third.
Pochettino rewarded Tom Carroll for his first Premier League goal in the 3-0 win over Norwich City with a starting berth, while he switched to a three-man defence with Kieran Trippier introduced as a wing-back for his top-flight Spurs debut.
Flores, meanwhile, made two changes at the back by introducing Ake and Ikechi Anya and Watford looked shaky defensively early on.
Gomes almost gifted his former club an opener in the 11th minute when he failed to claim Lamela's corner, but, fortunately for the Brazilian, Miguel Britos was on hand to head behind.
Spurs, though, were unforgiving when Watford made another mistake six minutes later.
Dele Alli caught Cathcart in possession on the halfway line and Lamela took full advantage, racing through and slotting the ball into the bottom-right corner.
Watford responded positively and Ighalo did his best to cause the Tottenham defence problems, but he failed to find the target with a near-post volley from Ake's cross with 25 minutes played.
But Ighalo did find the net for the sixth successive Premier League match before the interval.
The Nigerian showed strength to hold off the challenge of Eric Dier and bring down Troy Deeney's looping header before spinning past the defender and poking the ball under Hugo Lloris in the 41st minute.
Mousa Dembele had been struggling with a foot injury before kick-off and he was replaced before the interval.
Spurs continued to control possession after the restart and, with 58 minutes played, Harry Kane bundled an effort narrowly wide from Trippier's cross.
Tottenham's task was made easier five minutes later when Ake was shown a straight red card after he sent Lamela to ground with a high challenge.
Pochettino moved to introduce Son and the change paid dividends when the former Bayer Leverkusen man flicked Trippier's cross through the legs of Gomes in the 89th minute.
Claims for an offside against the South Korean in the build-up were ignored as Watford's five-game unbeaten streak came to an end.
Key Opta stats:
- Tottenham are undefeated in their last eight competitive games against Watford (W6 D2 L0).
- Spurs have lost just one of their last 18 Premier League matches, winning nine (D8).
- Watford scored with their only shot on target versus Tottenham.
- Erik Lamela has scored four goals in his last five games in all competitions for Tottenham.
- Harry Kane provided his first Premier League assist of the season and his first in 23 appearances
