Match ends, West Ham United 3, KRC Genk 0.
As West Ham took a significant stride towards the Europa League knockout stage with victory over Genk, forward Jarrod Bowen said "teams will be fearing us".
David Moyes' side maintained their 100% record after three games and comfortably sit top of Group H, six points clear of second-placed Dinamo Zagreb, who were beaten 2-1 at Rapid Vienna.
The Hammers had the majority of the possession but barely threatened in the first half until Craig Dawson looped home a header from Aaron Cresswell's cross on the stroke of half-time.
They took total control with two goals in the space of two minutes just before the hour mark.
Issa Diop headed in via the crossbar from another fine Cresswell delivery, while Jarrod Bowen cut in from the right and fired in shortly after, though goalkeeper Maarten Vandevoordt will be disappointed at not keeping the low drive out.
Bowen told BT Sport: "The main thing is topping the group. The home games are vitally important. We want to win away too.
"If we can stay strong, keep the confidence then I think teams will be fearing us. We could be the team to look out for. We're only a few games away from a big cup run.
"We'll keep pushing. We're winning games so that makes the players keep wanting to put the performances in."
West Ham were rampant and Nikola Vlasic could have converted a quick-fire fourth, but his shot from the edge of the six-yard box was blocked.
Genk were left to rue Paul Onuachu's big chance in the first half when he beat goalkeeper Alphonse Areola to a cross, but sent his header wide of an open net.
Hammers continue to impress in Europe
West Ham collected a hard-fought victory over Everton on Sunday and backed it up with another impressive showing in Europe, where they are gathering some real momentum.
They finished sixth in the Premier League last term to secure a berth in the competition and just one more victory will guarantee a route to the last 16.
They didn't have it all their own way on Thursday night against a Genk side that were champions of Belgium in 2019, qualifying for the Champions League where they finished bottom of a group featuring Liverpool.
The visitors thought they made the perfect start on eight minutes when Theo Bongonda headed in from close range, but the effort was ruled out for offside in the build-up.
Rangy striker Onuachu, who netted 35 goals last season, signalled a warning sign of his aerial ability when he headed over on the stretch before nodding wide when Areola came steaming off his line, but got nowhere near the ball.
That was Genk's most notable chance of the game and they were punished for not capitalising on it as their hosts showcased the difference in class.
Tomas Soucek, who played the full game despite undergoing plastic surgery to a facial injury suffered against the Toffees, saw a header pushed away by Vandevoordt.
Ben Johnson's low cross was then miscued by Bowen in the centre of goal, eight yards out, before centre-backs Dawson and Diop scored from headers either side of the break.
The contest was effectively over on 58 minutes when Vandevoordt failed to keep out Bowen's shot which was straight at him.
Asked about playing in the competition, Bowen said: "It means everything. Looking back and playing non-league, I remember scoring my first goal against Alfreton at 16/17.
"Now to score in the Europa League is a dream. I am loving every minute."
The lead allowed Moyes to bring off midfielder Declan Rice and Cresswell, handing a European debut to 19-year-old Daniel Chesters, before their meeting with London rivals Tottenham on Sunday (kick-off 14:00 BST).
'Everyone looking forward to away trips'
West Ham boss Moyes told BT Sport: "It was tight in the first half. I thought we deserved to go in front but they had one or two half-chances as well. But getting the goals quite quickly was great for us and allowed us to make a few changes and relax a bit more.
"We don't want to lose any goals. We had a couple of really good blocks late on and a few scary moments in the first half. We don't want that to happen but the players deserve it. The goal just before half-time was important.
"We have to go to Genk and Vienna. This is the bit everyone is looking forward to - the away trips for the fans, the players and the families as well. From that point of view it's still new, still fresh and we're really enjoying it."
- 3CresswellSubstituted forFredericksat 67'minutes
- 41RiceSubstituted forNobleat 67'minutes
- 10LanziniSubstituted forChestersat 89'minutes
- 11VlasicSubstituted forFornalsat 83'minutes
- 20BowenSubstituted forBenrahmaat 83'minutes
- 46CuestaSubstituted forSadick Aliuat 45'minutes
- 42ThorstvedtSubstituted forTomaat 83'minutes
- 7ItoSubstituted forOyenat 83'minutes
- 18OnuachuSubstituted forUgboat 73'minutes
- 10BongondaSubstituted forTrésorat 73'minutes
- 3Sadick Aliu
- Donatas Rumsas
- Shots on Target
Second Half ends, West Ham United 3, KRC Genk 0.
Corner, KRC Genk. Conceded by Ben Johnson.
Attempt blocked. Mike Trésor (KRC Genk) left footed shot from the centre of the box is blocked. Assisted by Luca Oyen.
Substitution, West Ham United. Daniel Chesters replaces Manuel Lanzini.
Attempt missed. Iké Ugbo (KRC Genk) right footed shot from very close range is too high. Assisted by Luca Oyen.
Offside, West Ham United. Saïd Benrahma tries a through ball, but Andriy Yarmolenko is caught offside.
Attempt blocked. Saïd Benrahma (West Ham United) right footed shot from outside the box is blocked.
Attempt blocked. Saïd Benrahma (West Ham United) right footed shot from the left side of the box is blocked. Assisted by Manuel Lanzini.
Substitution, KRC Genk. Bastien Toma replaces Kristian Thorstvedt.
Substitution, West Ham United. Pablo Fornals replaces Nikola Vlasic.
Substitution, KRC Genk. Luca Oyen replaces Junya Ito.
Substitution, West Ham United. Saïd Benrahma replaces Jarrod Bowen.
Foul by Nikola Vlasic (West Ham United).
Patrik Hrosovsky (KRC Genk) wins a free kick in the defensive half.
Nikola Vlasic (West Ham United) wins a free kick in the attacking half.
Foul by Patrik Hrosovsky (KRC Genk).
Jarrod Bowen (West Ham United) wins a free kick on the right wing.
Foul by Kristian Thorstvedt (KRC Genk).
Attempt blocked. Junya Ito (KRC Genk) right footed shot from the centre of the box is blocked. Assisted by Bryan Heynen.