Explained: Why isn’t Andy Robertson playing for Liverpool

Liverpool will welcome Porto in the first leg of the Champions League quarter-finals on Tuesday, but they will be without Scotland left-back Andy Robertson.

The tie will be a repeat of last season's round of 16 where Liverpool beat the Portuguese side 5-0 on aggregate. The Reds will be confident of a repeat of that result to progress to the semi-final stage of the competition, but minus the services of the full-back – who has been suspended for the tie.

Jurgen Klopp's side pulled off an incredible 3-1 victory away at Bayern in the previous round to reach the last eight of the European competition, though the result was slightly marred at the end when the Scotland international was given a yellow card for a mistimed challenge on Leon Goretzka late in stoppage time.

At 92 minutes, it was an unfortunate mistake to make so late in the game, as Robertson has impressed for the Merseysiders this season. 

"It's not cool but he is still a young boy," Klopp told BT Sport at full-time. "I asked the referee after the game and he thought it was reckless and whatever.

"Come on, it was last minute, nothing happened, he played the whole game unbelievably clean. But it happens. So we should not worry about things like that."

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Virgil van Dijk also played down Robertson's suspension, adding: "Yes. It happens in the game but obviously, it was a bit unlucky."

As it was his third yellow of the tournament, he is now suspended for the first leg of Liverpool's quarter-final battle. Additionally, yellow card accumulation is cleared following the round of 16, but that won't benefit Robertson at this stage of the competition.

Robertson will be available to feature for the second leg in Portugal, but his absence will give Klopp another selection headache in defence – as he had to make do with centre-back Van Dijk missing the first leg of the last 16 tie against Bayern Munich (also due to suspension), which ended in a 0-0 stalemate.

Joe Gomez is still battling with a long-term injury, while Alberto Moreno is another option at left-back to replace the Scotsman.

Liverpool will travel to Porto on April 17 to contest the return leg of the quarter-finals. Should the Reds progress to the last four, they will face either Manchester United or Barcelona.