The Monegasque won at Silverstone this month after seven-time world champion teammate Lewis Hamilton triumphed in Barcelona in June.
Mercedes have won the other seven rounds, with championship leader Kimi Antonelli taking five successive victories.
"For me, Silverstone and Spa are two tracks that will suit Mercedes a lot better," Leclerc told reporters at Spa-Francorchamps, the scene of his first F1 win in 2019.
"At Silverstone, it was honestly a surprise for us also to be strong. But we were also lucky on the Sunday because Kimi was probably as strong as what we expected.
"So, yeah, I think in Spa Mercedes is still the favourite."
Italian Antonelli, 19, started on pole position at Silverstone but lost out at the start and dropped to third before fighting back.
He was then slowed by a mechanical problem and a penalty for exceeding track limits and finished 16th - his second blank in three races - with his lead slashed to 25 points over teammate George Russell.
"Our car has been quick at every race, so for sure I’d expect us to be up there," Antonelli said of his Belgian prospects. "But Ferrari were also very strong at Silverstone.
"It was a surprise, but to be fair, we always kind of expected them to be up there because, especially when it comes to qualifying, they seem to find some extra time.
"So definitely we think they can be up there this weekend."