Pep Guardiola has never been able to escape the accusation that he owes his two Champions League titles as Barcelona coach to Lionel Messi, so the Manchester City manager might need to prepare for the same assessment of Erling Haaland if he ends a 12-year wait to win his third on Saturday against Inter Milan.

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It's a harsh appraisal of Guardiola to suggest that his success in the Champions League has relied heavily on his team boasting the world's best player at the time. But, equally, since leaving Barcelona in 2012, the 52-year-old has been unable win to the competition despite three seasons with Bayern Munich and six attempts, prior to this season, with City. He is now one game away from winning the Champions League at the seventh time of asking with City, but this time around, he has Haaland taking the Messi role as the one player who has proven to be unstoppable this season, with 52 goals in 52 games.

Messi was the X-factor in Guardiola's great Barcelona teams -- the Argentina forward was similarly central to Luis Enrique's team when they achieved a treble in 2015 -- and Haaland is the same for City now. The Norway international was signed for €60 million from Borussia Dortmund last summer as the missing ingredient in City's Champions League quest -- a reality the player admitted this week.

"This is why they bought me of course, to get this [Champions League]," Haaland told the BBC. "We don't have to hide that."

Guardiola's two Champions League-winning teams at Barcelona and this season's treble-chasing City side are about more than just one superstar player, but recent Champions League history also shows that, to win it, you need a forward who scores against all opponents in the biggest of games. When Barcelona won the Champions League in 2008-09, Messi scored nine goals in the competition and registered five assists -- 14 goal involvements. Two years later, when Barca were crowned European champions again, he scored 12 goals and registered three assists -- one better than in 2009.

This season, Haaland has already scored 12 Champions League goals for City, with one assist, and his goals alone have taken Guardiola's team to a new level. In each of Guardiola's six previous seasons as City manager, no player has come close to breaking the 10-goal barrier in the Champions League.

Winger Riyad Mahrez registered the highest return for Guardiola's side with seven goals in last season's competition. A year earlier, Ferran Torres was City's top scorer with four goals, while Raheem Sterling (six goals, 2019-20), Sergio Aguero (six in 2018-19), Gabriel Jesus (four in 2017-18) and Aguero again (five in 2016-17) emerged as top scorers with relatively low totals in Guardiola's other seasons with City.

When Manchester United won their third Champions League title in 2007-08, Cristiano Ronaldo top scored for Sir Alex Ferguson's side with eight goals and one assist, but it has become rare for a team to be successful in the competition without a striker as prolific as Messi or Haaland. Liverpool proved to be an exception in 2018-19 when they won their sixth Champions League with Mohamed Salah scoring just five goals and registering two assists, although Roberto Firmino and Sadio Mane weighed in with four goals each.

In 2013-14, Cristiano Ronaldo scored 17 goals, with four assists, on the way to helping Real Madrid win the competition, while Messi scored 10 and produced five assists a year later as Barca won their third Champions League in six years. With Madrid then dominating the competition by winning three consecutive Champions Leagues under Zinedine Zidane, Ronaldo was their clutch forward in each season. In 2015-16, he scored 16 goals with four assists. A year later, he scored 12 with five assists, and then in 2017-18, the Portugal forward scored 15 and created three assists. Even without Ronaldo, Madrid still had a player to regularly score goals when it mattered to win their 14th European Cup last season with Karim Benzema scoring 15 goals and creating two assists.

City's repeated failure prior to this season has been in part due to their inability to pull clear of opponents by taking advantage of half-chances to score in tight games. They often suffered exits by one-goal margins or on the old away goals rule after ties finished level on aggregate.

Haaland has been their game-changer, both in terms of volume and importance of his goals, scoring in both legs of the 4-1 aggregate quarterfinal win against Bayern Munich. He didn't score over two games against Madrid in the semis, but his mere presence on the pitch ensured more space for his attacking teammates to score in an emphatic 5-1 aggregate win.

City and Guardiola knew what they were getting when they signed Haaland. He now has 35 goals in 29 Champions League appearances at the age of 22, and official UEFA statistics show that, with 18 first-half goals and 17 in the second half, he is dangerous throughout the 90 minutes. He is the fastest player to 20 goals in Champions League history (14 games) and also to 30 goals (25 games.)

Only Sebastien Haller (six games) scored 10 goals in the competition quicker than Haaland, who took seven games to reach that mark. Ruud van Nistelrooy's record of 40 goals in 45 games looks certain to be the next one to fall to Haaland, while he could become the youngest, too, if he manages it before Kylian Mbappe's mark of 23 years and 317 days.

Just as Messi's peerless talent provided rocket fuel for Guardiola's Barcelona, Haaland's is having the same impact on Guardiola's City. But that's why City signed him. He is simply doing what he was expected to do -- score the goals to win the Champions League.