Matip missed over a month of action with an ankle injury and subsequent confusion over his withdrawal from international duty.
The defender returned for Liverpool's 3-2 defeat at Swansea on Saturday – coming on in the 89th minute.
He then played 60 minutes in an U23 game against Ipswich yesterday.
Liverpool player ratings against Swansea City
Sat, January 21, 2017
Express Sport rates the Liverpool players' performances from their clash with Swansea Cty at Anfield
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How did the Liverpool players get on against Swansea?
He was injured for six weeks, so the other players had to play nearly all the time
Klopp on Matip
Liverpool have kept five clean sheets in the 10 games since he last started for the club.
But Klopp says his team-mates are feeling the impact of picking up the extra slack over a busy Christmas period.
“It’s good because he’s a really good player.
“But he was injured for six weeks, so the other players had to play nearly all the time. So that’s the problem, not that Joel couldn’t play all the time.
Liverpool defender Joel Matip returned to U23 action yesterday
Matip (right) has not started a game for Liverpool since before Christmas
Jurgen Klopp's Liverpool lost 3-2 to Swansea on Saturday
“So he was not available but we had to cope with it.
“We are not happy with the last few results, but we understand it.
“Sometimes, there’s a single mistake, but most the time it’s seven or eight players. That’s how we understand it. It’s not about one player.
“We really have to do better.”