Match ends, Watford 2, Leicester City 1.
Watford boss Marco Silva says he was never worried about their bad form, as they beat Leicester City to end a six-game winless run.
The Hornets - who only had one shot on target in their 2-1 win - trailed when Riyad Mahrez headed the Foxes, now without a win in four games themselves, into the lead from Marc Albrighton's cross.
But Molla Wague equalised on his first Premier League start, against his former club, from close range and Richarlison then hit the post towards the end of the first half.
The Hornets' winner was a Kasper Schmeichel own goal as the keeper, while trying to keep Abdoulaye Doucoure's shot from a tight angle out of his goal, inadvertently turned it past his own line.
Heurelho Gomes made two excellent late saves to seal the win for Watford, from Wes Morgan's close-range effort and Leonardo Ulloa's header.
Watford had been only three points off the Champions League spots before a run of one point from six games.
Silva told BBC Sport: "We didn't lose our focus when we weren't winning, and now that we have won, I'm not going to be the happiest man in the world.
"I know clearly what is our reality as a club. You can have some fantastic results in a row but a season is too long. I know what can happen if you have lots of players banned or injured. It's impossible to win all our matches."
Watford end miserable run
Watford - without a win in over a month and with just one point from their last six games - looked as if they were going to endure a miserable Boxing Day when they trailed to Mahrez's header.
But to their credit, and boss Silva's delight, they showed great character to come back. He had to change his system when winger Roberto Pereyra came off with a knock, and was replaced by striker Stefano Okaka - with Richarlison moving out to the left wing.
And their fortunes changed from that point.
Some Leicester fans could almost be excused for not remembering Mali defender Wague, who had a one-game loan spell with the club last season. But they will remember him now, as he pounced late in the first half after the Foxes failed to clear a corner.
That goal lifted Watford, who had been below-par - or based on recent form, maybe playing at par. And Richarlison smashed the ball off the post two minutes later from Tom Cleverley's pass.
They continued that momentum into the second half. Cleverley's deep free-kick found Doucoure, who tried to beat Schmeichel at his near post from close to the byline. The ball might have been going across the goal when Schmeichel touched the ball past the line, with Ben Chilwell clearing from just behind the line.
Watford - who remain 10th - were indebted to their keeper, Gomes, for the win when he denied Morgan and Ulloa late on.
Leicester form starting to concern?
Stats can be used to prove whatever you want, and had Leicester won, then a 3-0 Crystal Palace defeat, followed by draws in 90 minutes against Manchester City - a penalty shootout defeat in the Carabao Cup - and United in the league, would not have been too troubling.
But their defeat by Watford means they have now failed to win in four matches, having lost only one of Claude Puel's first eight games in charge.
They deservedly led when Mahrez headed home Albrighton's excellent right-footed cross at the back post.
The Foxes should already have led at that stage when Albrighton played Jamie Vardy through on goal but he attempted to clip the ball over Gomes, and it fell wide.
Watford then scored twice - and hit the post - before Leicester rallied late on, with Morgan forcing a save from Gomes from six yards out and moments later Ulloa, who had just come off the bench, producing another fine stop from the Brazilian.
'It's a story about free-kicks' - Leicester reaction
Leicester boss Claude Puel to BBC Sport: "It was a little difficult playing against a physical team with long balls and second balls. The scoreline at half-time was a little harsh as we didn't concede a lot of chances.
"The second half was a bit more difficult. It's a story about free-kicks. We have to correct this situation for the next game. We were a little unlucky at the end as we had some fantastic chances, which Heurelho Gomes saved.
"A draw would have been a fair result. It's a big disappointment. We had a positive attitude."
Match stats - one shot on target, two goals
- Leicester have lost two of their last three in the Premier League, the same total they had lost in the previous 13.
- Mahrez has scored in each of his last four Premier League games against Watford, including in all three at Vicarage Road.
- Wague's goal means Watford have now had more different goalscorers in the Premier League than any other side this season (13).
- Leicester have only won one of their 12 Premier League games played on Boxing Day (D2 L9), losing each of the last four in a row.
- Watford scored twice despite landing just one shot on target, with the winning goal coming courtesy of Leicester goalkeeper Kasper Schmeichel.
- Marc Albrighton has assisted in consecutive Premier League appearances for the first time since April.
Man of the match - Molla Wague (Watford)
Watford host Swansea on Saturday (15:00 GMT), with Leicester away at Liverpool at the same time.
- 27KabaseleBooked at 13mins
- 22ZeegelaarBooked at 88mins
- 23WatsonBooked at 8minsSubstituted forPrödlat 87'minutes
- 28CarrilloSubstituted forSinclairat 90'minutes
- 37PereyraSubstituted forOkakaat 44'minutes
- 16DragovicBooked at 30minsSubstituted forGrayat 73'minutes
- 15MaguireBooked at 4mins
- 10KingBooked at 81minsSubstituted forUlloaat 84'minutes
- 20OkazakiSubstituted forSlimaniat 73'minutes
- Chris Kavanagh
- Shots on Target
Second Half ends, Watford 2, Leicester City 1.
Foul by Stefano Okaka (Watford).
Harry Maguire (Leicester City) wins a free kick in the defensive half.
Corner, Watford. Conceded by Ben Chilwell.
Attempt missed. Islam Slimani (Leicester City) header from the centre of the box misses to the left. Assisted by Marc Albrighton with a cross.
Substitution, Watford. Jerome Sinclair replaces André Carrillo.
Offside, Leicester City. Ben Chilwell tries a through ball, but Islam Slimani is caught offside.
Marvin Zeegelaar (Watford) is shown the yellow card.
Substitution, Watford. Sebastian Prödl replaces Ben Watson.
Attempt saved. Leonardo Ulloa (Leicester City) header from the centre of the box is saved in the bottom left corner. Assisted by Marc Albrighton with a cross.
Corner, Leicester City. Conceded by Heurelho Gomes.
Attempt saved. Wes Morgan (Leicester City) right footed shot from very close range is saved in the centre of the goal. Assisted by Harry Maguire.
Attempt blocked. Harry Maguire (Leicester City) header from the centre of the box is blocked. Assisted by Riyad Mahrez with a cross.
Substitution, Leicester City. Leonardo Ulloa replaces Andy King.
Corner, Leicester City. Conceded by Daryl Janmaat.
Attempt missed. Tom Cleverley (Watford) right footed shot from the right side of the box is close, but misses to the left.
Andy King (Leicester City) is shown the yellow card.
Richarlison (Watford) wins a free kick in the defensive half.
Foul by Andy King (Leicester City).