It wasn’t just a pair of his fancy cleats, stolen by an opportunistic thief just before kickoff in Munich, that Cristiano Ronaldo lost Tuesday.With a subpar performance in the game that began Real Madrid’s most important week of the season, the Portuguese superstar jeopardized a golden opportunity to threaten Lionel Messi’s mantle as the finest player in soccer.Ronaldo wasn’t bad in Madrid’s 2-1 defeat in the first leg of its Champions League semifinal against Bayern Munich, and the Spanish side is far from finished in this home-and-home encounter. However, the bar of modern excellence has been set, then raised, by Messi. And when Ronaldo had his chance to answer, when it mattered most, he came up short.There is nothing wrong with being the second best player in the world, especially in an era boasting Barcelona’s brilliant Messi. However, Ronaldo’s performance over the course of an exceptional campaign and his goal-scoring exploits had led some to suggest he could lay claim to Messi’s title as best in the world.To do that, he needs to match Messi’s feat from 2009 and 2011 by lifting both the Champions League trophy and the Spanish La Liga title.For all the highlight-reel moments and bullying of weaker opposition, this is the week Ronaldo faces his biggest challenge. Bayern came into its semifinal with the added incentive of this year’s final being staged at the Allianz Arena, its home stadium, and has given itself a healthy chance going into the return leg in Madrid.A powerfully struck goal by Franck Ribery and a dramatic last-minute effort from Mario Gomez secured a narrow advantage, with Madrid’s goal coming when Ronaldo set up Mesut Ozil seven minutes into the second half.Yet this was far from vintage Ronaldo. The swashbuckling, domineering style so often seen over the past several months was missing. Coach Jose Mourinho’s Madrid squad is blessed with more talent than its Bayern counterparts, and the Special One viewed this as an opportunity lost."The second goal came out of context,” Mourinho said."We were a better team in the first half but in the second the game was a bit broken and I didn’t like it so much. That’s football – they scored and we have to play in the second leg at home in a different atmosphere.”Madrid is a tough prospect for anyone on home soil, but winning will be difficult against a side that exhibited great desire and, according to coach Jupp Heynckes, more intelligence in the first leg."My players showed what I had demanded from them – lust and hunger for success,” Heynckes said."I think we more than deserved the win because we played cleverly and intelligently.”Ronaldo’s failure to find an extra gear does not bode well for the most critical clash of the La Liga season, as it prepares to visit Barcelona on Saturday, a contest that may decide the domestic championship.Just a few weeks ago Madrid justifiably felt it had the title wrapped up while sitting on a luxurious 10-point lead. For a few hours on March 31 the margin was back to nine, but it’s been since whittled away to a mere four.Ronaldo’s legacy would be far greater if not for his struggles in the most meaningful of matches, and rival Barcelona has been among his chief tormentors.This season’s first El Clasico was a case in point as Barca ran riot at the Nou Camp in recording a 5-0 victory.All talk of Ronaldo mounting a bid for the Ballon d’Or award given each year to the leading player in soccer would immediately disappear if Madrid was to be overhauled in the La Liga race and fail to find a way past both Bayern and the winner of the other Champions League semifinal between Barca and Chelsea.It is hard to criticize Ronaldo, who has scored at a rate of a goal per game since his world record $131 million transfer from Manchester United in 2009, but trophies, nerve and brilliance at the most crucial times provide the standard Messi continues to set.Ronaldo was fine Tuesday – but fine doesn’t cut it when measured against Messi.