The midfielder has been scarcely seen this season, totally just 11 minutes across four substitute appearances in the Premier League prior to the weekend.
Jurgen Klopp turned to him at Old Trafford with Liverpool trailing their rivals by a goal to nil.
And the 31-year-old was there at the back post to turn home Andy Robertson’s cross in the 85th minute.
It was Lallana’s first competitive goal since May 2017 - a fact he was well aware of.
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“I think it was against Middlesbrough, wasn't it?” Lallana said at full-time, per Goal.
"I've scored plenty in the back garden against my lad since then - didn't feel half as good, though!"
Amputee made Lallana bet
Lallana’s goal extended Liverpool’s unbeaten run in the league to 26 matches.
But not many Liverpool supporters had faith in the midfielder to make an impact, including amputee Andy Grant.
Grant, who became the world’s fastest single leg amputee over 10km in 2016, said on Twitter: “I will guarantee my leg will grow back” if Lallana did something positive after coming on.
“Lallana coming on? Let’s make a bet,” Grant wrote as the former Southampton player prepared to come on.
If Lallana does anything positive in this game I will guarantee my leg will grow back by next Friday.
Congratulations on the new leg, Andy.
Grant saw the funny side, following up his original tweet by writing: “Can’t wait to not be an amputee on Friday 👀”.
Lallana, aware of the busy schedule that awaits Liverpool, expects to see more action over the coming months.
“It's a long old season,” he added.
“We've got the Club World Cup to come. We've got the Carabao Cup next week, the Champions League this week, the Premier League at the weekend.
"Just because I've not started any of the first nine [league] games, I don't think that means I am not going to play a big part in this team. Football's a funny game.”News Now - Sport News