Bukayo Saka is one of only two players under 21 to score eight goals in one of Europe's top five leagues this seasonArsenal climbed into the Champions League places with an entertaining victory over lowly Watford in a game with five quality goals.
The Hornets, who remain in the relegation zone, thought they had taken the lead within the first 20 seconds as Emmanuel Dennis slotted home but he was offside.
Martin Odegaard put Arsenal ahead not long afterwards after flicking the ball into the path of Bukayo Saka and then running into the centre to slot in Saka's cross.
Watford levelled with the best individual goal of the game, Cucho Hernandez's acrobatic flying volley from Kiko Femenia's cross.
The visitors restored their lead when Saka won the ball off Tom Cleverley and found Alexandre Lacazette, who rolled the ball back into Saka's path to fire into the top corner.
England star Saka was involved again in the third goal as his quick throw-in set up a move with Lacazette laying the ball off to Gabriel Martinelli to finish.
They looked as if they were cruising, and Eddie Nketiah hit the post, before Moussa Sissoko controlled the ball on his chest and beat Ben White before slotting in.
That set up a tense finale with Watford debutant Samuel Kalu forcing Aaron Ramsdale into a save with a long-range shot.
Arsenal move above Manchester United into fourth spot for a couple of hours at least, with United facing Manchester City in the derby.
Watford, who blow hot and cold too often, remain three points off safety.
Arteta plays his part in Gunners' win
The Gunners continued their surge up the table with an entertaining albeit ultimately tense win, keeping them unbeaten in the league since New Year's Day.
They played some really top-quality, slick football, even though they only had four efforts on target and were hanging on in the end after Sissoko struck.
It could have been so different though had Dennis timed his run better before slotting in Joao Pedro's pass just seconds into the game.
But Saka was excellent again and involved in all three goals. He has scored or assisted 13 Premier League goals this season, with only Bayer Leverkusen's Florian Wirtz (17) involved in more in Europe's top five leagues among players under the age of 21.
Gunners boss Mikel Arteta had a big hand in the third goal, too, grabbing the ball after it went out of play and quickly passing it to Saka, who took the throw-in that led to the goal.
Watford played their part in an engaging contest - Arsenal's Aaron Ramsdale was the much busier goalkeeper - but have won just once under Roy Hodgson.
They become the fourth team to lose eight successive Premier League home matches, after Sunderland, Wolves and Norwich.
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Line-ups
Watford
Formation 4-3-3
1Foster
21Femenía15Cathcart22Samir14Kamara
19Sissoko6Louza8Cleverley
29Hernández25Dennis10João Pedro
1Foster21Femenía15Cathcart22Samir14Kamara19Sissoko6LouzaSubstituted forKayembeat 64'minutes8CleverleySubstituted forKaluat 89'minutes29HernándezBooked at 90mins25Dennis10João PedroSubstitutes
4Etebo11Masina12Sema26Bachmann27Kabasele28Kalu31Sierralta33Kucka39KayembeArsenal
Formation 4-2-3-1
32Ramsdale
17Cédric Soares4White6Gabriel3Tierney
5Partey34Xhaka
7Saka8Ødegaard35Martinelli
9Lacazette
32Ramsdale17Cédric SoaresBooked at 58mins4White6Gabriel3Tierney5Partey34Xhaka7Saka8ØdegaardSubstituted forHoldingat 90'minutes35MartinelliSubstituted forPépéat 73'minutes9LacazetteSubstituted forNketiahat 80'minutesBooked at 90minsSubstitutes
1Leno16Holding19Pépé20Tavares23Sambi Lokonga25Elneny30Nketiah69Swanson82HutchinsonReferee:Craig PawsonAttendance:21,142Live Text
Match ends, Watford 2, Arsenal 3.
Second Half ends, Watford 2, Arsenal 3.
Gabriel Magalhães (Arsenal) wins a free kick in the defensive half.
Foul by Moussa Sissoko (Watford).
Cucho Hernández (Watford) is shown the yellow card.
Attempt saved. Samuel Kalu (Watford) right footed shot from outside the box is saved in the top centre of the goal. Assisted by Moussa Sissoko.
Eddie Nketiah (Arsenal) is shown the yellow card for a bad foul.
Foul by Eddie Nketiah (Arsenal).
Moussa Sissoko (Watford) wins a free kick in the defensive half.
Substitution, Arsenal. Rob Holding replaces Martin Ødegaard.
Foul by Eddie Nketiah (Arsenal).
Samir (Watford) wins a free kick in the defensive half.
Substitution, Watford. Samuel Kalu replaces Tom Cleverley.
Foul by Eddie Nketiah (Arsenal).
Edo Kayembe (Watford) wins a free kick in the defensive half.
Foul by Bukayo Saka (Arsenal).
Hassane Kamara (Watford) wins a free kick in the defensive half.
Goal! Watford 2, Arsenal 3. Moussa Sissoko (Watford) right footed shot from the right side of the six yard box to the bottom left corner. Assisted by Cucho Hernández.
Attempt blocked. Emmanuel Dennis (Watford) right footed shot from outside the box is blocked. Assisted by Moussa Sissoko with a headed pass.
Foul by Thomas Partey (Arsenal).
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