Resurgent Williams have the same engine as the Mercedes works team and both Valtteri Bottas and Felipe Massa have been looking forward to Spa - and Monza in Italy after that - as their best chances of winning this season.
Spa is the longest circuit on the calendar and 70 percent of the 7.004 km lap is at full throttle - putting engine reliability and power at a premium.
The Mercedes power unit is the pick of the field and the four teams using it should be strong in Spa. Williams have already shown their car has both straight line speed and aerodynamic efficiency.
"I think in theory Spa and Monza should be the next really good ones for us, maybe the best opportunities of the season," Bottas said before Formula One embarked on its summer break after Hungary at the end of July.
Spa, the 12th of 19 races, marks the start of the decisive phase of the season with teams and drivers refreshed and raring to go.
Last year it proved the springboard for a remarkable run of nine wins in a row by Red Bull's Sebastian Vettel that culminated in the German's fourth successive championship.
There is no chance of that happening this time, even if Red Bull went into the break on the back of Daniel Ricciardo's victory at the Hungaroring. Vettel has been eclipsed by the Australian and is yet to get back on top of the podium.
"It will be damage limitation in the next two races, because Force India will suddenly reappear, Williams will be quick, McLaren will be quick and obviously Mercedes will be quick," said Red Bull team principal Christian Horner.
Even if Ricciardo intends to play as big a part as possible, the championship is a straightforward battle between Hamilton - the 2008 world champion - and his old friend and foe Rosberg.
Lewis Hamilton of Mercedes (AFP)
The pair are just 11 points apart and Hamilton recognised over the break, in an interview for sponsor Puma, that the battle felt more intense than his title tilts of 2007 and 2008.
"When I was racing against Kimi Raikkonen and Massa (then both at Ferrari), they were in a different team and their cars had different strengths and weaknesses to my car and, in my team, it was just me that was really competing with them," recalled the Briton.
"Now I'm racing against a guy who has the same car as me - we both have access to exactly the same data and feedback so it is really hard to try and be ahead.
"It's a little bit like playing poker - you have a set of cards and the other guy is not supposed to know what you got, but Nico and I can see each other's cards so then it's more difficult to beat each other."
In Hungary, he started from the pit lane and almost hit the wall on lap one but still finished third and ahead of Rosberg, who had been on pole. The Briton saw that as a possible omen.
"Hopefully that was a sign that my fortunes are changing at just the right time," he said.
Hamilton was on pole in Spa a year ago, and won in 2010, whereas Rosberg has yet to finish higher than fourth at a classic circuit that has long ranked as a favourite for drivers and spectators.
"It's good to be back after the break and to see everyone looking really refreshed and up for the fight in the remaining months of the season," the German, who finished fourth in Hungary, said this week.
"The (Spa) circuit is just unreal and it's one I think every driver looks forward to. My record there hasn't been as good as at some other circuits in the past, but I'm determined to change that and get the season kicked off again in style."
Ferrari, with Raikkonen and Alonso, will also be looking forward to returning to the Ardennes forests and the ever-capricious Spa weather.
Raikkonen, who has yet to beat Alonso this season, won at Spa four times in five visits between 2004 and 2009 and the 'Iceman' loves the challenge.
"Last time I drove here in a Ferrari, I won," the Finn recalled on the team website. "And that was in a year (2009) when we had been struggling since the start.
"It would be good if the same thing could happen this year."
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