Barça aware of Chelsea threat

After three epic encounters what new thrills does the fourth episode of the FC Barcelona v Chelsea FC heavyweight duel hold in store? In another eagerly-awaited confrontation the Spanish side hold a 2-1 advantage but with these two outstanding teams nothing can be predicted with any great certainty.

Two own-goals
• At Stamford Bridge on Matchday 7, Chelsea made light of their numerical disadvantage to take the lead through an own goal. That was swiftly wiped out as John Terry glanced a Ronaldinho free-kick into his own net before a tumultuous climax ensued with the visitors pressing hard for a winner. Lionel Messi hit the bar and Terry twice cleared off the line before Samuel Eto'o had the travelling supporters dancing with delight as a late far-post header divided the teams.

Another 2-1 lead
• Twelve months ago Barcelona had also ended the first leg of the first knockout round tie with a 2-1 lead but the difference was that they then had to go away to defend that advantage. This time the second game is at Camp Nou and Frank Rijkaard's team will be confident of gaining revenge for their 5-4 aggregate defeat last time.

Eto'o's a winner
• It was Eto’o who had also been responsible for their lead at the halfway stage 12 months before. Two weeks ago there were echoes of what had taken place then in the fact that Chelsea lost a man before half-time to a red card – Didier Drogba in Barcelona, Asier Del Horno in London – and also in the occurrence of own goals. Last year Juliano Belletti was the fall-guy in the first game as Chelsea took a surprise lead. Then substitute Maxi López inspired a fightback, scoring the equaliser and laying on Eto'o's winner.

One win apiece
• Aside from this season and last, the teams were drawn together in the 1999/00 UEFA Champions League quarter-finals, with Barcelona coming out on top. On that occasion a 5-1 victory at Camp Nou with two extra-time goals scored by Rivaldo and Patrick Kluivert earned them a 6-4 aggregate victory. The defeat remains Chelsea's biggest in 97 matches in UEFA club competition.

Formidable at home
• The result also strengthened Barcelona’s home record against English visitors. In 20 matches they have only once conceded ground, in the 1975/76 UEFA Cup semi-final when Liverpool FC won 1-0. Since losing 2-1 to Juventus in the Camp Nou in the 2002/03 quarter-final second leg they have won six and drawn one of seven UEFA Champions League home games.

Impressive statistics
• Three of those wins came in the group stage of this season’s competition. It was a comfortable passage for the Spanish champions as they finished with a nine-point advantage in Group C, their 16 goals establishing them as the most free-scoring team in the initial phase. At home they scored four against Udinese Calcio, five against Panathinaikos FC and three against Werder Bremen.

Last-eight regulars
• If Chelsea go out it will be the first time in four seasons of UEFA Champions League combat that they have failed to reach the quarter-final stage. Last year they progressed to the semi-finals for the second successive year, losing to eventual winners Liverpool by a single goal on aggregate.

• This season the English rivals faced each other again after they were paired together in Group G. Two goalless draws ensued but it was Liverpool who won the group with Chelsea finishing as runners-up, a single point behind. That was largely down to a 1-0 defeat in Spain, their last visit to the country, against Real Betis Balompié on Matchday 3.

Poor away
• Recent away games in the competition give the London side cause for concern in the Camp Nou, in a match that will be their 50th in the European Champion Clubs' Cup.

• They have won only one of their last seven - five of which have ended in defeat – which came on this season's Matchday 5, a 2-0 victory at RSC Anderlecht.

Only win in Spain
• And their record in Spain is not of great comfort either. Before this season's visit to face Betis they had played five games and lost all but one. Their only success was against Betis in the quarter-finals of the 1997/98 UEFA Cup Winners' Cup when they recorded a 2-1 victory.

Knockout format
• Clubs play two matches against each other on a home and away basis, with the team scoring the greater aggregate of goals qualifying for the next round. In the event of both teams scoring the same number of goals, the team which scores more goals away qualifies. If this proves inconclusive, extra time of two periods of 15 minutes is played after the second match. If during extra time both teams score the same number of goals, the away goals count double (ie. the visiting team advances). If no goals are scored during extra time, the winner is decided by penalty kicks.