Porto - FC Porto coach Sergio Conceicao reckons Liverpool are "the best team in the world" on their day as the Portuguese side face up to the daunting prospect of overturning a two-goal deficit in their Champions League quarter-final.

The teams meet at the Estadio do Dragao on Wednesday in the second leg of their last-eight tie, with Porto needing a historic comeback to go through after losing 2-0 at Anfield last week with Naby Keita and Roberto Firmino scoring.

While Porto have won all four home games in the Champions League this season, Liverpool travel to northern Portugal on top of the Premier League and unbeaten in 16 games.

"They are everything I like about football. I like the way they play, the way they are with the ball and without it," Conceicao said at an eve-of-game press conference on Tuesday.

"In my opinion, a lot of the time just now they are the best team in the world."

Porto lost 5-0 at home to Liverpool a year ago when the clubs met in the last 16.

Despite that, Conceicao, who also expressed solidarity towards Liverpool fans the day after the 30th anniversary of the "dark moment" of the Hillsborough disaster, was not giving up on turning the tie around.

However, he let slip that retaining the domestic title is Porto's priority during a lengthy rant at Portuguese authorities over match scheduling.

"We are two goals down against a side who we know are very strong going forward, and so keeping our balance when we are attacking will be fundamental to ensure we don't concede," said the coach, whose team are level on points with leaders Benfica at the top of the Portuguese league.

"It is difficult to prepare for this game because, incomprehensibly, we have another game on Saturday against Santa Clara.

"Why they don't protect teams like us? I have to ask what the main goal is for FC Porto, and it is the league."

Conceicao has a doubt over the fitness of Mexican wide man Jesus Corona, but veteran defender Pepe and captain Hector Herrera are both able to play after missing the first leg due to suspension.

"I saw that we are capable of damaging Liverpool," Herrera said of his view from the stand at Anfield.

"Here at home normally we are a very strong team with our fans behind us. I really believe that tomorrow will be no exception and we will be able to go out with that positive energy and hurt Liverpool."