West Ham climbed back into the Premier League's top four with a narrow victory over Roy Hodgson's Watford, as Kurt Zouma controversially started for the home side.
The Hammers have "unreservedly condemned" the France defender after a video emerged of him kicking his pet cat across the floor and slapping it in the face.
Zouma has apologised and the club have said they will deal with the matter internally.
Chances were at a premium in a dour first half at London Stadium, with Said Benrahma striking the outside of the post in the best opportunity of the opening 45 minutes.
Jarrod Bowen eventually broke the deadlock in the second half with his sixth goal in as many games - a long-range strike which struck Samir on its way past Watford goalkeeper Ben Foster.
Bowen almost doubled his and West Ham's tally late on with a fierce left-footed strike, but Foster was able to divert the ball on to the post.
The result stretches the Hornets' winless league run to 10 matches and leaves them stranded in the bottom three.Follow live text and radio commentary of West Ham United v Watford, plus Tuesday's two other Premier League matchesGo straight to all the best West Ham contentVisit our Watford page
Hammers shrug off controversy to edge tense encounter
Asked by BT Sport before the game whether the social media video of Zouma influenced his decision to play the defender, Moyes described the Frenchman as one of the club's "better players" and confirmed the incident is being dealt with as "a separate matter" by the club.
The 27-year-old was booed by large sections of the London Stadium whenever he touched the ball and endured a busy opening as Watford - despite seeing little of the ball - created the better opportunities.
Juraj Kucka headed narrowly wide after fine play from Hassane Kamara, before Moussa Sissoko dragged a long-range shot past Lukasz Fabianski's left-hand post.
West Ham, who needed extra time to defeat non-league Kidderminster in the FA Cup on Saturday, were non-existent as an attacking threat until late in the first half, when Benrahma was denied first by Craig Cathcart's last-ditch challenge, then by the frame of the goal as he drilled the rebound against the outside of the post.
Things failed to improve as a spectacle after half-time as the Hammers struggled to penetrate Watford's organised defensive line, but the visitors began dropping deeper and deeper as the half went on and eventually paid the price as Bowen netted what proved to be the game's only goal.
Tom Cleverley had a curling, goal-bound effort brilliantly saved by Fabianski late on, but Hodgson's team rarely looked like salvaging anything from the game after falling behind and now find themselves three points off safety after Newcastle's victory over Everton.
The Hammers, meanwhile, leapfrog Manchester United into fourth after the Red Devils were held to a draw at Burnley.
Fans pay emotional tribute
Poignant scenes preceded the match at London Stadium as supporters took part in a minute's applause for West Ham fan Isla Caton, who passed away in January aged just seven following a brave five-year battle with a rare neuroblastoma.
A message from Isla's mother was played on the big screen before the game, thanking fans for the "amazing love and support" Isla received during her illness.
Both sets of fans took to their feet for another round of applause in the seventh minute.
Player of the match
with an average of 7.99
West Ham United
Squad number20Player nameBowen
Squad number41Player nameRice
Squad number10Player nameLanzini
Squad number3Player nameCresswell
Squad number8Player nameFornals
Squad number9Player nameAntonio
Squad number28Player nameSoucek
Squad number22Player nameBenrahma
Squad number5Player nameCoufal
Squad number1Player nameFabianski
Squad number15Player nameDawson
Squad number4Player nameZouma
Squad number1Player nameFoster
Squad number25Player nameDennis
Squad number7Player nameKing
Squad number19Player nameSissoko
Squad number14Player nameKamara
Squad number8Player nameCleverley
Squad number22Player nameSamir
Squad number15Player nameCathcart
Squad number33Player nameKucka
Squad number39Player nameKayembe
Squad number21Player nameKiko Femenía
Squad number10Player nameJoão Pedro
Squad number2Player nameNgakia
Squad number6Player nameLouza
Formation 4-2-3-11Fabianski5CoufalBooked at 83mins15Dawson4Zouma3Cresswell28Soucek41Rice20Bowen8Fornals22BenrahmaSubstituted forLanziniat 60'minutes9Antonio
Formation 4-4-21Foster21FemeníaSubstituted forNgakiaat 78'minutes15Cathcart22Samir14Kamara33Kucka19Sissoko39KayembeSubstituted forLouzaat 77'minutes8CleverleySubstituted forJoão Pedroat 77'minutes7King25Dennis
Match ends, West Ham United 1, Watford 0.
Second Half ends, West Ham United 1, Watford 0.
Craig Dawson (West Ham United) wins a free kick in the defensive half.
Foul by Joshua King (Watford).
Foul by Jarrod Bowen (West Ham United).
Craig Cathcart (Watford) wins a free kick in the defensive half.
Attempt blocked. Emmanuel Dennis (Watford) right footed shot from outside the box is blocked. Assisted by Moussa Sissoko.
Attempt saved. Jarrod Bowen (West Ham United) left footed shot from the right side of the box is saved in the bottom left corner. Assisted by Tomas Soucek.
Vladimir Coufal (West Ham United) is shown the yellow card.
Corner, Watford. Conceded by Vladimir Coufal.
Substitution, Watford. Jeremy Ngakia replaces Kiko Femenía.
Substitution, Watford. Imrân Louza replaces Edo Kayembe.
Substitution, Watford. João Pedro replaces Tom Cleverley.
Attempt saved. Tom Cleverley (Watford) right footed shot from outside the box is saved in the top right corner. Assisted by Moussa Sissoko.
Attempt missed. Tom Cleverley (Watford) left footed shot from the centre of the box is high and wide to the left. Assisted by Joshua King following a fast break.
Corner, West Ham United. Conceded by Hassane Kamara.
Attempt blocked. Tomas Soucek (West Ham United) right footed shot from the right side of the box is blocked. Assisted by Aaron Cresswell.
Goal! West Ham United 1, Watford 0. Jarrod Bowen (West Ham United) left footed shot from outside the box to the centre of the goal. Assisted by Manuel Lanzini.
Corner, Watford. Conceded by Tomas Soucek.
Corner, Watford. Conceded by Vladimir Coufal.
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