Swansea manager Michael Laudrup believes Barcelona's Champions League exit proves they are reliant on the talents of Lionel Messsi.
Messi had struggled for fitness in the build-up and was an unused substitute at the Nou Camp for the 3-0 second-leg defeat to Bayern Munich, which sealed a crushing 7-0 aggregate loss.
Laudrup graced the Nou Camp as a player between 1989 and 1994, winning the European Cup in 1992, and feels the Catalan club have become too dependent on the Argentina forward.
"When they saw Messi was on the bench nobody thought it was possible to see a comeback (after a 4-0 first-leg defeat)," the Dane said.
"They have a great team but it's a little bit worrying that everything is related to the ability of Messi. Even if he is the best player in the world, it can be a problem."
Bayern advanced to a Wembley final against Bundesliga rivals Borussia Dortmund, who saw off Real Madrid in the other semi-final, but Laudrup thinks it is too early to suggest the German teams' success heralds a new era for European club football.
He added: "I know this is the year of the German sides and there are a lot of questions.
"Is it the end of Spanish football dominating? Are English sides struggling? We have to look to next year for the answers.
"If Borussia Dortmund and Bayern Munich are in the final in 12 months time and there are no English sides in the quarter-finals then we might have a new trend."
The Black Cats were feted as heroes on Wearside when in just the Italian's second game in charge, they went to Newcastle and won at St James' Park for the first time in almost 13 years, and their stock rose further six days later when a first victory over Everton in 20 attempts lifted them clear of the battle for Premier League survival.
However, Monday night's 6-1 drubbing at Villa Park left Di Canio's shell-shocked players contemplating a tricky run-in to the end of the season as they prepare to welcome Stoke to the Stadium of Light on Monday evening.
Their 44-year-old manager said: "After Newcastle, it was a three-day party for the fans, the players became heroes.
"I couldn't go 400 yards for a haircut. In Sunderland, there is a passion like Naples. You can't go out because a butcher comes out with meat saying, 'It's for you, for your family'.
"You couldn't go into the town, I couldn't believe it. Even in the street during the day, I went 300 hundred yards and 20 people stopped me.
"Many girls came and hugged me and I was wondering what was going on. I couldn't imagine this passion. I can imagine the players around the town.
"But we have to make sure for the future that there can't be too much positive poison because otherwise we are going to lose because we are worried, or because we have too much confidence.
"It's another experience for me. It was very tough, the first time I had lost 6-1 with my team in front of our fans at a crucial moment of the season.
"But because the analysis we made was clear, I am sure that we can lose, we can draw, we can win, but on Monday night, we are going to perform in a proper way. I can guarantee this."
Di Canio admitted his players had relaxed too much at Villa having seen Wigan pinned back by Tottenham at the death and Newcastle thrashed 6-0 at home by Liverpool two days earlier.
That meant victory for Sunderland would have all but secured their top-flight status, but it was to elude them spectacularly.
Di Canio said: "We felt safe. After Everton, we relaxed and at the weekend, the Wigan and Newcastle results gave us some poison because we went there and needed only three points.
"But we had to get the three points. As I said before, it has happened to me, I can understand. But it's not acceptable.
"The positive thing is it happened to a group of genuine players. They didn't do this because they wanted to lose 6-1 or because they are bad professionals.
"But we have to extend their motivation to always want more. It's not easy, you can't change their mentality in two or three weeks.
"You can change their habits, which is completely different in the way you approach the transition, but the mentality, how an individual can improve or how he can extend his desire to approach every game, even after three fantastic wins in a row, it takes time.
"My experience as a manager comes not because I studied football, but because I was a footballer with teams that were fighting against relegation or to win the league. The mentality is completely different.
"It happened to me at a lower level in a team that was fighting against relegation. We had a fantastic win against a top side, and the next week, we lost 7-1 against a side that at the end of the season, we finished above.
"It doesn't have to happen, but I know it happens. Fortunately, it was another experience for me."
