Rovers' impressive start to the season has seen their odds for promotion cut.
The bookmakers underestimated Rovers before the season started, but that has changed with Grant McCann's side sitting third in the Sky Bet League One table.
Sky Bet EFL trader Ivor Davies said: "McCann's Doncaster gained four wins and a draw in September and propelled themselves to third in Sky Bet League One.
"They were unlikely promotion candidates at the start of the season with double figures prices readily available but Rovers are now into 3/1 and Sky Bet will be keeping them onside."
John Marquis is one of the reasons for Rovers' strong start, with six strikes in five outings in September propelling him to the top of the division's scoring charts.
Sky Bet's Ivor added: "Doncaster are flying high in third place in Sky Bet League One and it's largely down to Marquis' six goals in five league games in September.
"He's currently on eight goals for the season and now sits as joint second favourite at 7/1 in the race for League One top goalscorer."