Barcelona host Chelsea, Real Madrid take on Juventus and Manchester United meet AC Milan as big-match glamour returns to the Champions League this week in the first knockout round.
Bayern Munich tangle with Arsenal in yet another showcase first leg game as the best 16 clubs in Europe start what should be a thrilling race to reach the quarter-finals.
Tuesday's matches: Last 16, first leg:
Bayern Munich v Arsenal
Liverpool v Bayer Leverkusen
PSV Eindhoven v Monaco
Real Madrid v Juventus
Holders Porto and Monaco, who contested last season's lacklustre final in Gelsenkirchen, face Inter Milan and PSV Eindhoven respectively.
Bayern could be one of three Bundesliga sides to qualify as Bayer Leverkusen face Liverpool at Anfield and Werder Bremen start with home advantage against Olympique Lyon.
The Nou Camp could well be hosting the best game for entertainment value, pitching together Europe's two form teams in Barcelona and Jose Mourinho's cash-rich Chelsea.
Barca, who knocked Chelsea out of the Champions League quarter-finals five years ago, have been in scintillating form nearly all season thanks to Brazil World Cup-winner Ronaldinho.
Frank Rijkaard's men have rattled up a seven-point lead in the Primera Liga with a top-scoring attack, led by African Footballer of the Year Samuel Eto'o, that reached 49 goals in Saturday's 2-0 win over Real Mallorca.
Chelsea are nine points clear at the top of the Premier League, though they suffered their first real setback of the season when a mainly second-string side were knocked out the FA Cup fifth round by Newcastle United on Sunday.
REAL DEFEAT
They also lost England wingback Wayne Bridge to a serious ankle injury at St James' Park, adding to injury woes that have already ruled out influential Dutch forward Arjen Robben and made Ivory Coast striker Didier Drogba a major doubt.
Barca's Liga title rivals Real Madrid endured a 2-0 defeat by Athletic Bilbao over the weekend as they prepared to face their former boss Fabio Capello, now in charge at Juve.
However, it was their first setback after a run of seven victories had put them firmly on Barcelona's trail and key players Zinedine Zidane and Raul were rested. Ronaldo was benched for failing to train properly during the week.
Manchester United, whose fans plan a torch lit protest before kickoff over a takeover bid by U.S. tycoon Malcolm Glazer, will be in a bullish mood at Old Trafford.
Unbeaten since October in the Premier League, where they lie second behind Chelsea, United have also been busy defending the FA Cup with a 2-0 win at Everton on Saturday that booked them into the quarter-finals.
Alex Ferguson should deploy on-form teenager Wayne Rooney in attack and will hope Dutch striker Ruud van Nistelrooy returns after being sidelined by injury since November.
United will also be buoyed by the knowledge that their defence is safe from Milan's European Footballer of the Year, Andriy Shevchenko, who is out after suffering a facial injury in Saturday's 1-0 win over Cagliari.
Former Old Trafford favourite Jaap Stam will be back in Manchester wearing a Milan shirt after a falling out with Ferguson led to the Dutch defender's unexpected exit in 2001.
Arsenal return to the scene of one their worst European performances when they take on Bayern at the Olympic Stadium.
Beaten 1-0 in a poor 2001 display, Arsenal now have injury problems at the back and are sweating on the fitness of their talismanic France striker Thierry Henry.
Their defence should be equally worried about the prospect of facing Bayern's Dutch striker Roy Makaay, who scored a hat-trick and set up two other goals in Saturday's 5-0 win over Borussia Dortmund.
