Dejan Lovren and Nathaniel Clyne both trained for Liverpool on Wednesday afternoon ahead of the visit of Manchester United to Anfield next Monday.
The pair were forced to drop out of international duty for Croatia and England respectively last week with knocks.
Centre-back Lovren sustained a groin problem in the final minutes of the Reds' 2-1 win over Swansea City before the break, while right-back Clyne played through the pain of a long-standing knee issue.
However, both have now fully recovered and trained without any hitches ahead of their monumental clash with bitter rivals United as Liverpool look for a fifth straight league win for the first time since March 2015.
But despite the positives of the return of the two defenders - who are expected to start alongside James Milner and Joel Matip - Liverpool have yet to welcome Georginio Wijnaldum and Adam Lallana back to training.
Summer signing Wijnaldum, who has featured in all seven of their Premier League games so far this term, pulled up with a hamstring injury in the Netherlands' 1-0 World Cup qualifying loss to France on Monday.
Wijnaldum and Lallana increasingly unlikely to play
Meanwhile fellow midfielder Lallana, who like Clyne had to drop out of England duty, was forced off mid-way through the first-half of the win at Swansea 11 days ago with an apparent groin complaint.
It would undoubtedly be a disappointing blow to lose either, or both, with Lallana in particular having been crucial to the side - being nominated for September's Man of the Match award.
It's likely that Jürgen Klopp will have to alter the look of his midfield three against Jose Mourinho's men, with Emre Can one of those in the frame to come into the team.
Klopp could also drop Philippe Coutinho deeper into the centre, as he has Lallana, with the Brazilian having done so in the absence of the injured Englishman in South Wales.
Among the others back in training were Belgium duo Divock Origi and Simon Mignolet, neither of whom played on international duty.
Coutinho and compatriot Roberto Firmino, as well as England contingent Jordan Henderson and Daniel Sturridge, won't report back at Melwood until later in the week - though they should still have plenty of time to train ahead of the United fixture.
The visitors have a few doubts of their own, with Luke Shaw and Henrikh Mkhitaryan fighting to be fit - but Phil Jones will definitely miss out with a serious knee injury.