Cristiano Ronaldo makes a big difference for Portugal. When an ankle injury kept him out of Portugal's first two European Championship qualifying games, the team drew at home against Cyprus and lost to Norway. When the captain returned, Portugal racked up a five-game winning streak that put them back in contention.
Portugal's problem, however, is that the squad lacks depth and, beyond Ronaldo, top-class talent in some key positions.
As with previous greats Eusebio and Luis Figo, Ronaldo's presence lifts the team a notch. The Real Madrid forward was Portugal's top scorer in its qualifying campaign, with seven goals in eight games, and is the country's third-highest scorer with 32 goals in 87 appearances.
Portugal coach Paulo Bento, mindful of the weight on Ronaldo's shoulders, is eager to stop the expectations from becoming a burden.
"We're going to avoid putting pressure on any one player," Bento said. "We know what value, talent and commitment Ronaldo has given us but we won't put him under pressure to resolve the team's problems."
That may be easier said than done for a team that so far hasn't looked like one of the continent's best despite being ranked fifth in the world by FIFA. Portugal are the odd one out in what is arguably the tournament's toughest group as rivals Germany, the Netherlands and Denmark are all past winners of the tournament while the Portuguese are still chasing their first international title.
Portugal came close to collecting their first silverware at Euro 2004, when they lost to Greece in the final. At the 2006 World Cup, they reached the semifinals. Since then, they has rarely impressed.
Perhaps Portugal's biggest shortcoming is the absence of a world-class center forward. Helder Postiga and Hugo Almeida have had disappointing seasons at their clubs but they have remained first-choice strikers in a Portugal team that gets most of its goals from midfield players. The pair together scored seven goals - the same as Ronaldo - in qualifying.
When Ronaldo is absent Portugal look to Nani, who missed the 2010 World Cup because of injury. But the winger, despite some spectacular goals, hasn't made the same impact as Ronaldo with Portugal or Manchester United.
There is also a question mark over the right back and left back positions. Fabio Coentrao has been inconsistent on the left of Real Madrid's defense, while Sporting Lisbon right back Joao Pereira is seen as a lightweight. There is no obvious replacement for either of them.
The most encouraging development for Portugal is Bento's career as national coach.
When he replaced Carlos Queiroz in September 2010 after Portugal earned only one point from its first two qualifiers, Bento's only previous senior coaching experience was at Sporting Lisbon between 2005-09.
But Portugal recorded five straight victories after he took charge. And crucially, Ronaldo regained his goal touch under Bento. Ronaldo scored three times in his first four appearances under Bento after finding the net only twice - once from the penalty spot - in 18 matches with Queiroz.
Bento has also broadened the squad by trying out a series of uncapped players and has recalled others sidelined under his predecessor.
"The change (of coach) brought new blood and a change of mentality, and Paulo Bento should be congratulated," Ronaldo said.
Despite the improvements, Bento, a former defensive midfielder who played for Portugal at Euro 2000 and at the 2002 World Cup, is aware that it's a big ask at Euro 2012 to get Portugal beyond the group stage - a hurdle it has never before failed to clear.
"It's a very difficult group," Bento conceded. "We'll have to be at our best to reach the following round."