He has been nicknamed 'Harry' by his manager Graham Westley because of his wizardry and it was magical performance by the former Dulwich Hamlet man as he scored one and created one as Peterborough United ran riot at the ABAX Stadium.
Gabriel Zakuani set Posh on their way with a powerful header before Oztumer doubled the advantage before the break as Posh missed countless opportunities in front of goal.
Australian Callum Elder scored his first senior goal moments after the re-start and Conor Washington completed the scoring with a fine finish from 20-yards as Darren Ferguson suffered a heavy defeat on his return to the ABAX.
Boss Westley was not getting carried away in the post match press conference, just happy to see an improvement in his young side at both ends of the pitch.
Erhun Oztumer curled a left-footed free-kick wide of the target inside the opening few minutes as Posh made a lively start.
Souleymane Coulibaly, restored to the starting line-up, tested Stuckmann with a fierce drive and from the follow-up, his acrobatic over head kick went wide.
Oztumer tested the keeper again with a curling effort and from the resulting corner kick, Posh were ahead as a driven set-piece was met by the head of ZAKUANI who powered home from 10-yards.
Coulibaly cracked the post with a stunning left-footed effort and then Taylor was a whisker away with a curler as Posh continued to be rampant.
However, Posh were forced into a change on 17 minutes as Michael Smith replaced the injured Zakuani. Bostwick moved into centre back as part of the change.
A raking pass from Almeida Santos picked out Washington on 21 minutes, the striker took a superb first touch, but he couldn't finish.
Cedric Evina fired over from 25-yards for the visitors as Posh failed to clear a right-wing centre from Williams.
Washington fired across goal, inches away from Coulibaly on the half hour as Posh ripped apart from the Donny defence with some slick one-touch football.
Almeida Santos was cautioned for a foul after the referee had already given a free-kick in Doncaster's favour - he did clatter into his man by the touchline though.
The lead was doubled on 36 minutes and Coulibaly can take a lot of the credit, excellent hold up play and then picked out the onrushing OZTUMER who fired home past a flat-footed Stuckmann.
Posh wasted another great chance on 38 minutes as Oztumer and Washington combined to pick out Coulibaly, but after beating the offside trap, he took a heavy touch and Stuckmann pounced on the loose ball.
Doncaster made a change at the interval with Aaron Taylor-Sinclair replacing Chaplow. However, within 60 seconds, Posh were 3-0 to the good and if at first you don't succeed, try, try again. ELDER'S initial shot was goalbound but smacked into the face of a defender, however it rebounded kindly into his path and the Australian loanee stabbed home with his right-foot.
Bostwick cleared a Butler header off the line from a corner kick as Doncaster tried to get themselves immediately back into the contest.
Anderson saw a deflected effort go straight at Stuckmann after good work from Washington in the build-up.
Tyson fired a volley onto the inside of the post on 54 minutes after a right-wing centre, Alnwick reacting quickly to catch the ball as it headed for him.
Alnwick was called upon to make his first save of the afternoon on 64 minutes, beating away a fierce effort from the experienced Coppinger.
Posh made a change on 66 minutes, Andrew Fox replacing Jermaine Anderson. Alnwick made a routine stop to deny a skidding free-kick by Stewart after Fox was penalised for a foul.
It was 4-0 to Graham Westley's men on 71 minutes as Conor WASHINGTON fired home from 20-yards past the despairing dive of Stuckmann.
Posh made an immediate change with Lee Angol replacing the excellent Oztumer. Fox fired a free-kick into the wall before Taylor saw a shot shoveled away by Stuckmann.
Nathan Tyson fired wide with his left-foot after Angol was dispossessed in the middle of the pitch as Doncaster came close to pulling one back.
Substitute Angol provided a decent opportunity for Coulibaly on 82 minutes, but the former Tottenham man fired wide of the near post.
Forrester was denied by a fine stop by Alnwick as his free-kick floated over the wall while Fox screwed a shot wide from distance at the other end.
Posh: Alnwick, Zakuani (sub Smith 18min), Taylor, Bostwick, Oztumer (sub Angol 74min), Almeida Santos, Washington, Anderson (sub Fox 66min), Coulibaly, Elder, Forrester. Unused subs: Henry, Vassell, Davey, Collison.
Doncaster: Stuckmann, Lund, Evina, McCullough, Butler, Wellens (sub Middleton 54min), Chaplow (sub Taylor-Sinclair 46min), Williams, Tyson, Coppinger, Stewart. Subs: Marosi, Forrester, N'Guessan, Keegan, Horsfield.
Half-time: Peterborough United 2-0 Doncaster Rovers
Full-time: Peterborough United 4-0 Doncaster Rovers
Attendance: 6,092 (646 Doncaster fans)