The 29-year-old clocked up half an hour as a substitute for England in the friendly draw with Italy at Wembley on Tuesday night.
Jürgen Klopp had been in talks with Three Lions boss Gareth Southgate before the international break about managing Lallana’s fitness following the long-term thigh injury and subsequent setbacks that have limited the No.20 to a dozen Reds appearances this term.
He returned to Melwood on Wednesday and is now ready to make up for lost time as Liverpool face Crystal Palace this weekend, Manchester City in the Champions League quarter-finals and Everton in between.
“I feel I’m physically and mentally as fresh as anyone going into the back end of the season and going into the World Cup,” said Lallana.
“I’m fully fit now. I had to manage myself, probably for the first couple of days, hence why I wasn’t involved over in Holland, but it’s been a great end to the week. Personally, it is great to be back out there in an England shirt for the first time this season, since last summer.
“I go back to my club now and I’ve got Palace at the weekend, then Manchester City, then the Merseyside derby, then City. So it doesn’t stop.”
While the frustration of missing so much football has yet to dissipate, Lallana is consoled by the fact his return coincides with the most important section of the season.
Liverpool’s dual objective is ongoing progress in the Champions League – with the two-legged tie against City to kick off at Anfield on Wednesday – and securing a place in the competition for next season by claiming a top-four Premier League finish.
The England international also has this summer’s World Cup on his mind.
“It’s been a different challenge for me this year. I’ve had a long lay-off but I’m back for the business end of the season and I’ve got to look at the positives,” said Lallana.
“I’ve got a World Cup coming up, some really important league games, and the quarter-finals of the Champions League. So if I had to be back fit for one part of the season then it’s the back end, the business part. I’m raring to go.”