Jürgen Klopp has explained the rationale behind the decision not to register Jon Flanagan for the knock-out phase of the Europa League.

The 23-year-old has recently returned to first-team action with appearances against Exeter City and Stoke City after a knee injury had kept him on the sidelines since May 2014.

However, Klopp explained why Flanagan hasn't been included in the Reds’ European squad, with a decision taken to err on the side of caution with the full-back's fitness following such a lengthy spell out.

He told journalists at Melwood on Friday: “With Jon, it was 18 months [out injured]? So the best news is that Jon is involved, back in the race and back on the pitch. That’s really good.

“But in this moment, it’s like it is – it’s really early after his injury, so we always have to be careful when he’s playing. I always get the [medical] advice, and Flanno needs two or three days’ recovery [after games] – not because he thinks he needs [it], but only because of the seriousness of the injury.

“And so I had to make decisions with the European squad. It’s not my hobby to disappoint players, especially not Flanno who has done nothing wrong until now. But it’s three games a week. We will have two more games in the Europa League for sure, but hopefully a lot more, and they’re always between other games.

“We’ve had a problem with Martin Skrtel [getting] re-injured, he needs another two or three weeks, and so in the centre-half and offensive situations we’ve had our problems and in the end, you cannot believe how difficult it is to make a European squad.

“It is always difficult because you think of this player, or this player, but in this moment with Flanno’s history this year, the decision was like this.”