Gianluca Scamacca came off the bench to score the only goal as West Ham moved a step nearer to qualifying for the Europa Conference League knockouts with a deserved 1-0 win at Anderlecht.
The much-changed visitors - manager David Moyes made nine changes from Saturday's 2-0 home win over Wolves - dominated the group B clash at the Constant Vanden Stock Stadium, only for some poor finishing to leave the game scoreless approaching the final 10 minutes.
- Europa Conference League groups | Fixtures | Results
- How the teams lined up | Match stats
- Download the Sky Sports App
However, Moyes was rewarded for an attacking triple substitution with 20 minutes left to play, with two of those subs combining for the winner as Lucas Paqueta set up Scamacca to net his fifth goal for his new side.
As a result, West Ham made it three wins out of three in the group and are now within touching distance of playing in Europe after Christmas.
How West Ham maintained winning run in Europe
Despite making a massive nine changes from the weekend win over Wolves, West Ham still bossed the early exchanges in Brussels and should have gone in ahead at the break.
However, Said Benrahma had clearly left his shooting boots at home, with the Algeria playmaker spurning a number of gilt-edged chances, none more so than when he blazed over a gaping goal having been picked out by Jarrod Bowen's cut back five minutes before half-time.
The second period was closely fought, but the game turned on a triple substitution made by Moyes with 20 minutes remaining as the West Ham boss introduced the likes of captain Declan Rice, as well as recent new signings Paqueta and Scamacca in attack.
And it took that duo less than 10 minutes to team up for the winning goal as the Brazil international's clever flick released Scamacca on goal and from a tight angle, the Italian found the bottom left-hand corner of the net with pinpoint accuracy.
But the visitors owed their victory to a sensational reflex save from No 2 Alphonse Areola, who somehow managed to keep out Fabio Silva's 84th-minute close-range header when it seemed certain the on-loan Wolves striker would level matters.
Thanks to that late stop, the Hammers now need just four points from their last three group games to guarantee a place in the knockouts next spring as Moyes and Co look to go one better than their semi-final appearance in last season's Europa League.
Moyes: West Ham showing signs of return to form
West Ham manager David Moyes:
"We want to try and get going - I think the players are beginning to show signs of getting back to form," he said.
"We're beginning to get one or two goals. I think we should be scoring more, but a clean sheet and the team winning is always good.
"Anderlecht hadn't conceded any goals in the group stage previously, so it was always going to be tight.
"We missed a hatful of opportunities to score and made it a bit scary for ourselves, but overall I thought we deserved the victory.
"I don't think you're seeing anybody win by big margins in this competition. Football throughout Europe is really competitive and it was another tough game tonight."
Hammers super subs offer glimpse of exciting future
Analysis by Sky Sports' Richard Morgan:
When substitutes Gianluca Scamacca and Lucas Paqueta teamed up cleverly for West Ham's late winner against Anderlecht, it offered a real glimpse of what the duo could offer David Moyes's side in attack this season.
The Europa Conference League clash featuring the top two in group B was finely balanced when David Moyes decided to roll the dice and make a triple change with just 20 minutes left at the Constant Vanden Stock Stadium.
The Hammers manager introduced Scamacca and Paqueta in a show of real strength from the bench and soon they had combined neatly on the edge of the Anderlecht box to maintain the visitors' 100 per cent record in the competition.
Scamacca still had work to do to find the far corner of the net after good skill by his Brazilian team-mate had created the opening, but he did it unerringly for his fifth goal for the club since joining from Sassuolo for £35.5 million in July.
And expect the Italy international and Paqueta, who arrived from Lyon for £51m the following month, to start at home to Fulham on Sunday.
What's next?
West Ham return to Premier League action on Sunday as they host Fulham, with kick-off at 2pm.
The Hammers will then play their return match against Anderlecht at the London Stadium on Thursday, with kick-off at 8pm.