Liverpool travel to FC Porto on Wednesday as their Champions League campaign resumes with a Round of 16 first-leg tie at the Estadio do Dragao.
The Reds are unbeaten in their four previous meetings with the Portuguese Primeira Liga leaders, who were one of the last teams to book their place in the knockout stage as runners-up to Besiktas in Group G.
In the most recent encounter with Os Dragoes, during the 2007-08 Champions League group stages, a Fernando Torres brace helped the Reds secure a 4-1 victory at Anfield.
Dirk Kuyt's 17th-minute strike in the reverse fixture had earned Rafa Benitez's side a 1-1 away draw earlier in the competition.
The Reds will be hoping to maintain that unbeaten record on Wednesday and we've picked out three key battles that could help decide the match in Portugal...
Alex Telles vs Mohamed Salah
Brazilian left-back Telles exerts a huge influence on Porto's attacking game and was linked with a move to the Premier League during the January transfer window.
The pacy full-back starred under Nuno Espirito Santo at Estadio do Dragao last season and has kicked on again under current boss Sergio Conceicao, providing 16 assists in 34 games across all competitions.
The former Gremio, Inter Milan and Galatasaray defender loves to deliver the ball from out wide and made more accurate crosses from open play (44) than any other player in his domestic league last season. He is also an expert at dead-ball situations.
However, the 25-year-old can expect his defensive duties to be put to the test by Liverpool's leading goalscorer on Wednesday. LFC's No.11 has been in scintillating form in his debut season for the Reds, scoring 29 goals in 35 games - including the second strike in Sunday's 2-0 Premier League win at Southampton - through a combination of mazy solo runs, 30-yard net-busters and simple tap-ins.
The Egyptian has also provided 10 assists from his starting position out on the right flank and his head-to-head contest with Telles looks like being one of the highlights of the match.
Danilo Pereira vs Alex Oxlade-Chamberlain
Guinea-Bissau-born Danilo Pereira was part of Portugal's victorious squad at Euro 2016 and has been the anchor at the base of Porto's midfield under successive managers since 2015.
The 26-year-old sits in front of the back four and is wonderfully described as an 'octopus' by the club's official website - presumably due to his ability to win the ball back for his team in all manner of situations. His tally of 34 interceptions in the Primeira Liga is impressive, but his aerial prowess - winning 75 per cent of his duels - is unsurpassed by his midfield peers.
Danilo's physical prowess also enables him to operate as a box-to-box midfielder and he has come alive in the Champions League this term, scoring three goals and providing one assist in six games in the competition. He was one of a number of key players rested by Conceicao for Sunday's 4-0 away win at Chaves.
Oxlade-Chamberlain could well be the player that Jürgen Klopp selects to test Porto's octopus. The summer signing from Arsenal can operate all across midfield, but three of his four goals for the Reds, and all four of his assists, have come when playing in the central role he reprised against Southampton on Sunday.
Strong on the ball and capable of carrying possession from deep, Oxlade-Chamberlain delivered a man-of-the-match performance against Manchester City's highly-rated defensive midfielder Fernandinho during the Reds' headline-grabbing 4-3 triumph at Anfield - scoring the opener and then turning provider for Roberto Firmino.
Yacine Brahimi vs Trent Alexander-Arnold
African Footballer of the Year-nominated trio Yacine Brahimi, Moussa Marega and Vincent Aboubakar are the headline acts of Conceicao's Porto.
Algeria forward Brahimi pulls the strings coming in from the left flank, with Mali international Marega and Cameroon striker Aboubakar applying the finishing touches up front in a flexible 4-4-2 formation.
While this attack-minded structure has served Porto well domestically, in Europe, Conceicao has often opted for a 4-2-3-1 or 4-3-3 setup, with the versatile Brahimi pushed forward into the front three.
The 27-year-old loves to dribble with the ball and he leads the Portuguese Liga with an incredible tally of 111 take-ons - obliterating the 49 registered by Estoril's Victor Andrade in second place.
The Porto No.8 is also excellent at unlocking defences with his pass selection and has notched eight goals and nine assists in all competitions this season.
With Joe Gomez still returning to full fitness following a knee injury, fellow right-back Alexander-Arnold will likely be the man tasked with halting the supply line from the Porto playmaker.
The pacy defender, who loves to get forward, has played in four of Liverpool's six Champions League fixtures this season, keeping a clean sheet in three of them, scoring and providing an assist.