Even given the rich history of Brazilian football, the race for the 38th Brasileirao crown is unlike anything seen previously. Since 2003, when the introduction of a conventional league format ended more than three decades of experimentation, there has never been a title race so open or exciting.

In 2003, Vanderlei Luxemburgo's Cruzeiro were unstoppable, finishing the season 13 points clear of nearest challengers Santos. And while in the following two years the championship battles were a lot closer, they were both only two-horse races: a Robinho-inspired Santos held off Atletico Paranaense in 2004, while a Corinthians side boasting Carlos Tevez eventually took the title by three points from Internacional of Porto Alegre 12 months later.

Sao Paulo, leaders of this year's Brasileirao with just four rounds remaining, had nothing like the same competition for top spot in their back-to-back triumphs in 2006 and 2007, when they finished nine and 15 points clear of Internacional and Santos respectively.

"," said Sao Paulo coach Muricy Ramalho, who is chasing his third successive league crown with the team from the Morumbi. Indeed, few sides have risen to the challenge as well as O Tricolor Paulista, who extended their unbeaten run to 14 games on Saturday with a 3-2 win at Portuguesa that kept them top on 65 points.

The race for the title has been wide open for several matchdays but, with the finishing line approaching, the main contenders are now rising to the occasion

Muricy Ramalho after his Sao Paulo side made it 14 games unbeaten at the weekend to stay top.

Though not out of the running at the halfway stage in the campaign, the reigning champions had little cause for optimism back in August. Since the current format was introduced in 2003, the leader at the halfway stage had always gone on to take the title. All the signs, therefore, pointed to 2008 revelations Gremio, who hit the front on Matchday 14 and led for 17 rounds in total.

In fact, the Porto Alegre outfit were still setting the pace until nine days ago, when they dropped back to third place. Last weekend, however, they showed their stomach for battle with a crucial away win over title rivals Palmeiras. Gremio are now just two off the pace on 63 points, while Cruzeiro, who edged Fluminense 1-0, and Palmeiras lie two points further back on 61. Nor should Flamengo, on 60 points, be discounted either, after Sunday's 1-0 win over Botafogo in their Rio derby.

The effect of this late-season parity is clear to everyone involved, not least Gremio midfielder Souza. "For anyone who likes football, the 2008 Brasileirao has been an excellent tournament. This year we've had excitement like never before," the player said after his side's hard-fought victory over Palmeiras. "From here on in, all the games will be like that one - real battles. The permutations are endless and one result could change the scenario completely," added his coach Celso Roth.

Vanderlei Luxemburgo, who has won a record five Brasileirao titles as coach, was reminded again this weekend of just how quickly a team's fortunes can change. His Palmeiras side went into their meeting with Gremio buoyed by their derby win at Santos, only to find themselves down in fourth on Sunday night. "It's not that we've thrown in the towel, just that we have to be realistic. If we had beaten Gremio, then we'd be going toe-to-toe with Sao Paulo. Now our priority has to be to secure a Copa Libertadores place."

Despite the experience of having won the last two championships and the run that has taken them back to the summit, the leaders categorically dismiss any talk of favouritism. "Now is when everyone will be trying to label us with that tag, so we need to be careful and constantly remind ourselves that, hard as it was to take top spot, it will be even harder to hold on to it," warned Ramalho.

Indeed, with four rounds left and just five points separating the top five, it still looks too close to call.