Manchester - Jurgen Klopp admits the clock is ticking on his target of winning a trophy within the first four years of his Liverpool tenure but after eliminating Manchester City he says he dare not dream that it will be the Champions League.

The 50-year-old German refuses to contemplate a sixth European crown for the historic club even after they beat the runaway Premier League leaders 5-1 on aggregate in the quarter-final to reach their first Champions League semi-final for a decade.

In his first season, Klopp guided Liverpool to the 2016 Europa League final where they lost to Sevilla but he is now contemplating a leap upwards in terms of quality of opposition.

"I said (at his unveiling as Liverpool manager) if I sit here in four years probably we won something, otherwise it's not possible," Klopp told reporters after the 2-1 second-leg victory over Pep Guardiola's team on Tuesday.

"It's now two and a half years and I still haven't won anything so time is running."

Klopp, who guided Borussia Dortmund to the 2013 Champions League final where they lost to bitter German rivals Bayern Munich, says it is far too early to claim Liverpool can be the equals of European giants Bayern Munich and Real Madrid.

Bayern and Real are potential semi-final opponents should they come through their quarter-finals unscathed on Wednesday. And a huge obstacle to all the teams' chances of lifting the trophy was removed on Tuesday with AS Roma's miraculous dismantling of Barcelona.

"I have absolutely no interest in comparing us. Barca, Bayern, Real Madrid they win everything in the past 20 years," said Klopp.

"You don't become a winner overnight."

Liverpool do of course have a rich Champions League history, most recently with the miraculous comeback in the 2005 Champions League final against AC Milan in Istanbul, although the Italians gained revenge in the final two years later.

Klopp says his side are still a work in progress.

A big step in that direction has come with his gamble to outlay a world record fee for a defender to acquire Virgil van Dijk. The Dutchman has added much-needed defensive solidity.

"We can only develop," said Klopp. "This competition is unbelievably strong.

"I don't care who is in (the draw), we are there and we deserved it and so far we fought for each opportunity to get it and then used it.

"That's what we will do (in the semis) but the other sides are not without their ambitions."

However, the laidback side of Klopp - he admits he finds time to be a bookworm - is reflected in how he felt he would have preferred to have watched the match.

"You cannot imagine how much intensity you feel before a game like this," he said.

"Everybody wrote me a message: 'I will watch the game here, there, I'll have a beer together with friends'.

"I would really like to do that as well sometimes, drink beer and watch a Champions League game. Unfortunately it is all work."

Come May 26 in Kiev he may at last be able to down a beer or three should Liverpool fulfil his personal ambition and restore the term European giants to their name.