Watford, who went into the game with just one defeat in their last six league games, got off to the perfect start when they scored via a throw-in. Younes Kaboul's long throw was headed on by Deeney to Stefano Okaka, who then teed up the Watford captain to volley past Fraser Forster from close range. It was Deeney's 105th goal for Watford and moved him alongside Cliff Holton as the joint-fourth highest goalscorer in Watford history. Southampton pressed for a reply and it came from some poor Watford defending. The Hornets failed to clear a loose ball and it came out to an unmarked Tadic in the 18-yard box, who drilled his shot into the bottom corner.
Redmond then put the Saints into a deserved lead in first-half stoppage time. It was a lovely worked goal, started by the England under-21 winger who played the ball to James Ward-Prowse. He in turn found Tadic on the right, who then cut back for Redmond to squeeze his shot into the far post. Manolo Gabbiadini was Saints' most in-form player going into this game, having scored five goals in his first three games since a £14m move from Napoli in January. The Italy striker, who scored twice in the cup final, should have netted on 56 minutes as he outstripped Miguel Britos down the left flank, cut inside but then wasted a golden opportunity. Linking with the excellent Tadic and Redmond, the Saints front three caused Watford plenty of danger on the break.
It was a surprise when Okaka levelled and the Italy striker should have put Watford ahead five minutes later with a two-on-one. Just 30 seconds later and Watford were punished as Gabbiadini scored his sixth for the club. Heurelho Gomes spilt Sofiane Boufal's shot and Gabbiadini pounced to become the first Saints player to score in his first three Premier League appearances for the club. Okaka's wastefulness was punished further by Redmond who lashed a shot past Gomes, just a minute later.
Southampton manager Claude Puel said: "I'm unhappy about the third Watford goal, but it was important to get a good result after our big disappointment against Manchester United. "It was important my players showed their character to come back from a goal down, they played directly, we kept concentration and we recovered and played good football and scored beautiful goals. "Now we have two weeks without a game and this is difficult." On Gabbiadini: "It was important to find a player who can give the team a good efficiency, a clinical edge. It is interesting for the confidence of the team and other strikers."