Ten-man Lyon dropped points in Ligue 1 for the second straight match as Sylvinho's side were held to a 1-1 draw at the Groupama Stadium by Bordeaux.
A busy transfer window and thumping victories in their opening two games of the season had raised hopes that Lyon could challenge reigning champions Paris Saint-Germain for the title.
But the midweek 1-0 loss to Montpellier was followed with another disappointing performance, as Jimmy Briand grabbed Bordeaux a point midway through the second half after Memphis Depay's opener and Thiago Mendes' sending off.
"The sending off of Thiago Mendes penalised us. It seemed to me that it was an exaggerated (fall)," said Sylvinho, who replaced Bruno Genesio as Lyon coach in May.
"I am sad about the result and the sending off."
Depay fired the hosts into a 32nd-minute lead with a low, left-footed strike after racing away from the visiting defence and has now scored four league goals in as many games this season.
But the dismissal of Mendes, a close-season signing from Lille, for a second yellow card changed the match and Briand equalised in the 67th minute after a goalmouth scramble.
"It's very hard to digest, clearly two points lost, but the good thing is that we did not lose," said Lyon goalkeeper Anthony Lopes.
"We lacked focus and maturity to finish the game XI against XI."
Rennes will put Ligue 1's last 100 percent record on the line against Nice on Sunday, but only need a point to retake top spot from PSG, who beat Metz 2-0 on Friday.
Elsewhere on Saturday, promoted Brest suffered their first defeat of the season with a 3-0 loss at Nimes, while Angers moved into third by beating pointless Dijon 2-0.