Ricardo Santos grabbed a stoppage-time goal as Peterborough recorded their first win in eight Sky Bet League One games by beating Doncaster 2-1.It stretched the luckless home side's dismal run without a victory to 13 games and dumped them into the bottom four.Rovers did manage to score the opening goal for the first time in 10 home games when a mistake from Santos led to Andy Williams crossing from the left for skipper James Coppinger to fire home.But Posh did not let their heads drop and they hit back to equalise before the interval. Star man Marcus Maddison sent over a superb low cross from the right and Aaron Williams slid the ball home at the far post.Doncaster looked the better side early in the second half with Cameron Stewart having a header saved before Nathan Tyson was denied by visiting goalkeeper Ben Alnwick.Aaron Williams caused home keeper Thorsten Stuckmann to make an awkward save in the 85th minute before setting up the winner deep into added time.He headed against the post and Santos latched on to the rebound to atone for his earlier error and grab his first goal for the club.