Cristiano Ronaldo has plenty of experience turning a nearly hopeless cause into a triumph.
He was the lead figure in a Real Madrid team that battled hard, but helplessly, to wrest the Spanish league title from Barcelona for two years before finally topping its archrival in the 2011-12 season.
Now, Ronaldo is in the process of triggering another reversal of fortune with Portugal at the European Championship.
He has been booed, whistled and taunted for two inexplicably wasteful games that put the Portuguese on the brink of elimination. Then he came alive with two goals in a come-from-behind 2-1 win over the Netherlands which earned Portugal a spot in the quarterfinals.
"Now everything is possible," Ronaldo said after the win over the Dutch.
Next stop in his splendid season, in which he scored 60 goals for Madrid, is Thursday's match against the Czech Republic when a spot in the semifinals is at stake.
Portugal's run in the tournament mirrors the relentless determination Ronaldo showed against the Dutch. The Portuguese only reached the tournament via the playoffs after finishing runners-up in their group following their worst start to a qualifying campaign in 14 years.
Add to that the lack of a single victory in its warmup games for Euro 2012, a drop from No. 5 to No. 10 in the FIFA rankings, an opening loss to Germany and Ronaldo misfiring in the first two games in a group where it was the lowest-ranked team.
Then, with three minutes to go against Denmark, substitute striker Silvestre Varela finally kickstarted Portugal's campaign with the winner in a 3-2 victory.
Little wonder the underdog tag would suit Portugal, even though they should be favored to beat the Czechs.
"From now on, there are no longer any favorites," said midfielder Raul Meireles, who has his own comeback story.
He was in the Chelsea side which seemed headed for a lost season until a charmed spring under a temporary coach won the London club a first Champions League title.
Petr Cech also played a massive part in Chelsea's end-of-season rally and the veteran goalkeeper will try to keep Ronaldo and Meireles at bay in Warsaw.
With just as much opportunism as Meireles, Cech said: "It's clear who the favorites are. But we'll be trying to prove that the favorites don't have to necessarily always win."
The Czech team has its own comeback story. They were written off by many after losing to Russia 4-1 in their opening match but responded with a pair of victories over Greece (2-1) and Poland (1-0), and now hope to reach the semifinals as they did at Euro 2004 in Portugal.
"We've passed two huge tests," Cech said. "We came back and have a chance to equal our success from Portugal. We just need to win one more game."
Czech Republic coach Michal Bilek has a major injury concern after captain Tomas Rosicky left the team's base in Poland to return to Prague for treatment of an Achilles tendon problem that forced him to miss the match against Poland. He rejoined the training base in Wroclaw on Tuesday but must pass a fitness test on the eve of the quarterfinals.
Rosicky picked up the injury during Tuesday's 2-1 win over Greece and hasn't trained since. The Arsenal playmaker said he has only a small chance of recovering for Thursday.
Without him, the Czechs are likely to struggle against Portugal.
"We all know he's irreplaceable," Bilek said.