Liverpool could be missing several key stars for the clash with Villarreal in the Champions League in midweek, as an important night at Anfield awaits

Liverpool is missing three more stars from training on Monday ahead of the Champions League clash with Villarreal, adding to Andoni Iraola's current availability concerns.

It follows the Reds hosting an open training session ahead of the European encounter at Anfield on Tuesday, where the full squad will once again be put to the test. The fixtures have come thick and fast for Iraola and his team, with matches against Manchester City, LASK, and Brentford all coming within six days.

Attention turns to a Villarreal side capable of causing problems, with Liverpool needing to be alert for the Champions League encounter, knowing it will be tough.

The challenge for the head coach will surround the balance within his team. While he will want to put out a competitive side capable of winning the tie, he will also be acutely aware of the players' fitness levels that need to be maintained, so the side can remain competitive in upcoming fixtures across all competitions.

Considering how thin the squad is in general, it doesn't take much for the depth to be exposed, as the injury issues have begun piling up once again.

That much has become clear in the wake of the Brentford victory, when both Jeremie Frimpong and Dominik Szoboszlai had to be withdrawn during the game through injury. Neither player was present at open training, and it is likely to be some time before they are available again.

“Jeremie Frimpong is obviously a new muscle injury, and it happened, I think, in the second or third minute he was playing, difficult to predict, and we will have to wait until he recovers," Iraola admitted in his pre-match press conference before Villarreal. "But it’s going to be difficult, I think, before the [November international] break. We will try, but it’s going to be difficult to have him.

“Dom Szoboszlai is different," he continued. "It’s not a new injury, I think it’s in the same place it was probably last week. He hasn’t worsened the injury but probably we have to be a little bit more patient until he recovers fully. But it’s not like something now where he has to wait a lot of time to come back, he is more or less in the same situation he was last week.

“But we need more patience with him, but I appreciate the effort he did the other day, to be available, to want to contribute in a very difficult game that you know is going to be very physical – [against] one of the most physical teams, Brentford. And to put himself in front and to want to play speaks very well about him, yes.”

While those two were predicted not to be involved anyway, there has been further concern as Victor Munoz was not spotted in the open training session either.

The winger has impressed this season, scoring the all-important equalizer for Liverpool against Brentford, before he seemingly picked up an issue in the latter stages of the match.

While it's unclear whether he will be available, as the Spaniard may have been doing some individual work in the meantime, it does raise some concern.

“Obviously Victor is a player that we know very well," Iraola also said in his pre-match press conference. " I also have a great relationship with Alessio Lisci, who was his manager [at Osasuna] in the past season. He speaks also very well.

“Once you have a player, you really understand what he gives to the group. Attitude-wise, I think he is ready to help in whatever position we need him. He is playing right, left, the other day he played right-back.

“I think he is a player with hunger. He hasn’t played professionally in a big club like Liverpool but he has been in the academy of Barcelona, has been in the academy of Real Madrid, has trained with those teams. He knows the level that is required in those teams. Also with the national team he is having experience. So, he is a player that is adapting really well, yes.”

It remains to be seen what could follow for Liverpool, as Iraola must put out a team capable of competing against Villarreal on Tuesday, given the existing injuries to Giovanni Leoni, Conor Bradley, and Hugo Ekitike.