Philippe Coutinho and Emre Can have handed Liverpool manager Brendan Rodgers a big fitness boost ahead of the new campaign after coming through their first pre-season appearances of the summer unscathed.
Both players featured for 45 minutes of the 2-0 Under-21 defeat to Porto after returning to training on 21 July, following summer exploits with their respective international sides.
Coutinho's Brazil reached the Copa America quarter-final while Can's Germany were beaten semi-finalists at the Under-21 European Championships in the Czech Republic. The duo had been given extra time off to recuperate ahead of the new season.
Neither player travelled on Liverpool's four-match summer tour of Asia and Australia but they are now in contention to feature in the final pre-season game before the new campaign against Norwegian side HJK on 1 August, prior to the Premier League opener against Stoke City.
The news is a key boost for Liverpool with memories of Adam Lallana and Jose Enrique missing the start of last season through injury still fresh, while Daniel Sturridge was rushed back to the first team for the first three league games before falling to an ongoing thigh problem.
Liverpool Under-21 coach Michael Beale said to the club's official website: "It was fantastic to have Philippe and Emre with us and they did really well in the planned 45-minute outing. Their attitude was absolutely fantastic and they were brilliant in the dressing room as well with our young lads.
"It was exciting for the supporters at Corby Town to see players of the calibre of Philippe and Emre in action, and I've been lucky to work with them in training this week. Overall Porto were much older than us and are ahead of us in their physical preparation at this stage.
"The penalty was very harsh for the second goal and I think even the Porto players were quite surprised when it was given. I've been pleased with the players though this weekend. We have faced two tough games against very good opposition.
"We had the chances to beat PSV but just couldn't find the winner, and again today we had some good openings but were guilty of trying to get the perfect goal. I'm very pleased with our work so far though and we face Chester's first team on Wednesday before playing Morecambe's first team next Saturday, so they will be two good tests for us."