London: European heavyweights Barcelona and AC Milan must overturn one-goal deficits when they take on north London's finest in the second legs of their Champions League last-16 matches this week.
Arsenal visits Barcelona on Tuesday vowing not to simply sit back and defend the 2-1 lead the team earned in a riveting first leg at Emirates Stadium on Feb. 16.
Milan has a much tougher task on Wednesday, with the Italian leaders trailing Tottenham 1-0 going into the second leg at White Hart Lane.
In the two other second-leg matches in Europe's elite club competition this week, Ukraine's Shakhtar Donetsk hosts a Roma side looking to overcome a 3-2 deficit on Tuesday, while Schalke and Valencia are level at 1-1 ahead of Wednesday's game in Germany.
The Barcelona-Arsenal match is set to be the standout fixture, especially if the English side honors its pledge to go on the attack at the Camp Nou, where it was outclassed 4-1 in last season's quarterfinals en route to a 6-3 elimination on aggregate.
Arsenal playmaker Samir Nasri said his team couldn't replicate the style of Inter Milan, which stifled Barca by defending in numbers at the Nou Camp to eliminate the Spanish champions in the semifinals last year.
"We must rely on our game if we want to win. We can't play another game to stop them. We are not Inter Milan," Nasri said. "We don't have the same qualities as Inter Milan. We don't have a Walter Samuel, Marco Materazzi or Esteban Cambiasso to kick everyone.
"We have players who love football, who want to play attractive football. We will go to the Nou Camp and play our game. We are confident we can beat them."
While Arsenal goes into the game on the back of Saturday's disappointing scoreless draw with Sunderland that stalled its Premier League title charge, Barca defeated Real Zaragoza 1-0 to stretch its unbeaten run in the Spanish league to 25 league matches — one short of the club record set in 1973-74.
Lionel Messi has scored 43 goals and set up 21 more in 39 games this season and will attempt to reproduce his exploits of last year against Arsenal, when the Argentina forward struck four times at the Camp Nou in an inspired individual display.
"We will see if they take us on like last year," Barcelona midfielder Xavi Hernandez said. "They have players that can make the difference and there will be a lot of spaces on the pitch. But if we have the ball and (stay true) to our personality, we have good chances to win.
"It could be a problem for them having won the first game. They have the doubt if they should go for the game or try to protect their lead. It is not a team prepared to defend."
Barcelona coach Pep Guardiola will be without center backs Gerard Pique (suspended) and Carles Puyol (leg injury), so Eric Abidal or Gabriel Milito could come in.
Arsenal will be without striker Robin van Persie and winger Theo Walcott, but central midfielders Cesc Fabregas and Jack Wilshere should win fitness battles to start.
Milan, a seven-time European champion, has won four straight matches in Serie A to stand five points clear of city rival Inter, but found Spurs' pace and quick passing too difficult to handle in the first leg at San Siro on Feb. 15.
Milan defender Thiago Silva still believes his team has a chance to go through.
"It will be a very difficult match for us in London, but we can do it," Silva said. "The important matches always go right to the end, and with the team we have, we can do that too."
Kevin-Prince Boateng is struggling to be fit for the clash with his former club after coming off injured in Milan's 1-0 win over Juventus on Saturday. The Italians' midfield will already be missing injured pair Andrea Pirlo and Massimo Ambrosini, and suspended midfielder Gennaro Gattuso.
Winger Gareth Bale should start for Spurs after returning to action Sunday in a 3-3 draw at Wolverhampton Wanderers, having missed the last six weeks with a back injury. Playmaker Rafael van der Vaart should also feature despite a recent calf problem.
"We're at home and we have to go and try to win the game. It's not natural for us to sit on a 1-0 lead for 90 minutes," Tottenham manager Harry Redknapp said. "We will pick an attacking team and have a go at them, that's how we have to play."
Valencia will have top scorer Aritz Aduriz available after an ankle sprain when the Spanish team, which is third in its domestic league, travels to Schalke.
New Roma coach Vincenzo Montella, meanwhile, is confident he can maintain his 100 percent away record since taking over as coach and overturn Shakhtar Donetsk's advantage.
Since Montella succeeded Claudio Ranieri, Roma has won twice away, the latest a 2-1 victory against Lecce.
"We have the team to do it," Montella said. "We have to go there to try to win because we have a squad that is capable of doing so."
Shakhtar will rely on their phalanx of Brazilian stars, three of whom — Jadson, Douglas Costa and Luiz Adriano — scored in the first leg in the Italian capital.