Claudio Ranieri's return to Leicester ended in disappointment as Brendan Rodgers' side returned to winning ways in the Premier League with a 4-2 victory over Watford in snowy conditions at the King Power Stadium.
The former Leicester boss, who led the club to the Premier League title in 2016, was given a hero's welcome by the home fans before the game, but his side were behind in the 16th minute after James Maddison capitalised on an error from William Ekong.
However, Watford responded well and deserved their equaliser on the half-hour mark when Josh King netted from the penalty spot after Emmanuel Dennis was brought down by Wilfred Ndidi in the penalty area.
The snow started to fall heavily in Leicester making conditions difficult, but it did not stop Jamie Vardy as his quickfire double (34, 42) sent the hosts into the break with a commanding lead.
Watford got back into the game in the 61st minute when Dennis pounced to score after Timothy Castagne's error, but they failed to build on the goal and Leicester made the game safe just seven minutes later when Ademola Lookman scored his first Premier League goal for the Foxes (68).
Victory sees Rodgers' side end a run of three games without a win in the top flight to move up to ninth in the table, while defeat keeps Watford in 16th, four points clear of the drop zone.
- How the teams lined up | Match stats
- Premier League results | Table
- Get Sky Sports | Live football on Sky Sports
In pictures: Ranieri's Leicester return...
How Leicester ruined Ranieri's King Power return...
Watford had shown enough to suggest they could worry a Leicester defence lacking in confidence only for Ranieri's side to gift the hosts a 16th-minute lead.
Jonny Evans launched a harmless ball forward which should have been comfortable for Ekong but the defender ducked underneath expecting Daniel Bachmann to collect. He had not seen Maddison stealing in behind him and the midfielder seized the chance by finding the corner of the net.
Watford were undeterred, though, and Kasper Schmeichel denied Dennis before Cucho Hernandez's 20-yard strike hit Caglar Soyuncu and looped onto the inside of the post.
If Leicester thought they had escaped they were mistaken as Watford continued to press and got their reward from the spot after half an hour. Ndidi's reckless trip on Dennis gave referee Andrew Madley little option and King beat Schmeichel for his fifth goal of the season.
Yet the Hornets were undone four minutes later by a piece of Maddison brilliance. The 25-year-old clipped an exquisite pass over the top for Vardy and he lifted the ball over an advancing Bachmann from an angle, celebrating in front of his old boss.
Eight minutes later the former England striker made it 3-1 when he again combined with Maddison to glance in his corner.
Vardy scored 24 times when Ranieri took Leicester to the title in 2016 and had given the Italian a reminder of his talents.
Yet the Foxes needed Schmeichel to thwart King from close range after Hernandez - who should have tried a shot himself - teed him up soon after the break.
As the snow got worse so did Leicester's defending and Watford grasped a lifeline when Dennis robbed Castagne to dink over Schmeichel.
But it was another false dawn as Lookman added a fourth for the Foxes, tapping in Harvey Barnes' cross soon after.
A stretching Ozan Tufan poked just wide for Watford with six minutes left but there was no way back.
What the managers said...
Leicester boss Brendan Rodgers: "It was great, you can see Maddison's quality, he was a real inspiration for us.
"We always have a point to prove every single day. For him it was looking at his game, he knows this is a game and a level where you are always looking to prove yourself. You can never be calm with that, you always have to be intense.
"You are seeing the work, not just with him but the confidence returning to the team. It's not about the one player, it's about the team but he was excellent today.
"It was a really good performance, we were a real threat going forward. We were playing against a dangerous team, they scored five at Everton, four in their last game against Manchester United. It's an important three points."
Watford boss Claudio Ranieri: "The reception was fantastic, I want to say thank you to all the fans, Leicester and Watford fans. They came here on this very difficult day and I want to say thank you because I hope they are proud of us.
"We fought 'til the end. We created more chances than Leicester but they scored and we didn't. I am positive because it's important the team try to create chances.
"We conceded four goals so we can do much better but they won the match because they were more aggressive and more determined than us.
"It was Christmas Day conditions. It wasn't the pitch, we lost because we made mistakes and Leicester scored the chances they had."
Man of the match - James Maddison
It looked like the Maddison of old.
He was at the heart of everything Leicester did well, scoring his side's opener before setting up both of Vardy's goal before the break.
He was a constant threat to Watford with his clever positioning and passing, and Leicester will be hoping he can keep this good form going as we approach the busy festive period.
Opta stats: Leicester get back to winning ways...
Leicester registered only their third win in their last 10 Premier League matches (D3 L4) - despite this, the Foxes shipped two goals for a fifth consecutive home Premier League game, the first time they've done that since a five-game run between April and August 2001.
Watford have conceded in each of their last 23 Premier League matches, shipping 45 goals in the process, the longest current run of any Premier League side without a clean sheet.
With his two goals in this game, Leicester's Jamie Vardy equalled Ian Wright's record of scoring 93 goals in the Premier League aged 30+. Since his first game aged 30 in January 2017, only Harry Kane (108) and Mohamed Salah (106) have more Premier League goals than Vardy.
Vardy has scored in five of his six home Premier League appearances against Watford, netting six goals, the joint-most he's scored against an opponent at the King Power Stadium for Leicester, along with both Arsenal and Liverpool.
What's next?
Leicester go to Southampton at 7.30pm on Wednesday evening in the Premier League, while Watford host Chelsea at the same time. Free highlights from both games will be available on the Sky Sports website, App and YouTube channel.