Liverpool may have to surrender the advantage of playing at home in the second leg if they reach the semi-finals of the Champions League.
The Reds are 2-0 up against Porto after a win at Anfield in the quarter-final first leg ahead of tomorrow's clash in Portugal.
And the reward if they get past the Portuguese champions this week is a mouthwatering last-four clash with either Barcelona or Manchester United.
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As it stands, the draw has Liverpool down to play the first leg of a potential semi away with the second leg at Anfield.
However, if Manchester City and Manchester United both progress to the semis then Liverpool's last-four tie would be reversed.
It may seem unlikely at this stage given United are 1-0 down against Barcelona going into the second leg and City face a tough test against Spurs, given they trail by the same scoreline.
But under UEFA rules, two clubs from the same city aren't allowed to play at home on the same day or even on consecutive nights.
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As United finished lower than City in the Premier League last season, United's fixture would have to be moved.
That means if it's Liverpool v United in the semis - and City are still in contention for glory - then the Reds would face Ole Gunnar Solskjaer's side in the first leg at Anfield with the second leg at Old Trafford.
