The opening stages were fairly even until David Clarkson saw red in the 25th minute for an elbow on the excellent Josh Scowen.
Wanderers took complete control of the game after that, but struggled to break through a well-organised defence until Jon-Paul Pittman’s low strike was only parried by Steve Mildenhall and Kretzschmar fired into the empty net.
Gareth Ainsworth made one change from the side that beat Torquay United 3-2 last Saturday with the available-again Charles Dunne replacing Sam Wood. Gary Doherty and Matt McClure were named on the bench after recovering from illness.
Matt Ingram was called into action early on and he did well to palm away Seanan Clucas’ header after the midfielder had met Ryan Brunt’s cross from the left.
Ellis Harrison then blasted well wide after a clearance had fallen to the winger inside the area.
Blues’ first chance fell to Kortney Hause, but his header from Jo Kuffour’s cross was tipped over by Steve Mildenhall. From the resulting corner Dunne saw a header cleared from near the line.
The best early chance came in the 16th minute when Dunne and Matt Bloomfield linked up on the left and the former found Kuffour in the area, who acrobatically fired over the bar from eight yards.
Dunne saw a goalbound shot cannon back off Will Packwood’s head with the defender knowing little about the effort.
The hosts were reduced to 10 men in the 25th minute when Clarkson was shown a straight red card for an elbow on Scowen. Referee Darren Sheldrake initially waved play-on, but after consultation with his assistant he gave the striker his marching orders.
Knott fired over after Rovers failed to clear a Scowen free-kick, and the midfielder came even closer 10 minutes before the break when he fired just wide after a neat passing move that saw Cowan-Hall knock the ball down for the Sunderland loanee on the edge of the area.
Hause headed Arnold’s corner wide after eluding his marker, before Anthony Stewart had the final chance of the first half. The centre-back broke forward after another spell of prolonged Wanderers possession and jinked past one defender before curling
goalwards from 25 yards, but Mildenhall was well positioned and made a simple stop.
Chairboys continued to see a lot of the ball after the break, but were still restricted to long-range efforts and Lewis drilled wide from 30 yards just before the hour mark.
Knott stung the palms of Mildenhall from 20 yards and Ainsworth made his first change in the 62nd minute, bringing on McClure in place of Kuffour.
Max Kretzschmar was introduced five minutes later at the expense of Bloomfield with Jon-Paul Pittman coming on in the 76th minute.
That change almost paid off instantly as McClure cut in from the right and his shot deflected into the path of Pittman, who was denied by a fine save from close-range.
However, the Wanderers weren’t made to wait much longer as they took the lead five minutes later. Scowen found the lively Pittman and his low shot was parried away by Mildenhall, but only to Kretzschmar, who fired high into the roof of the net for his third of the season.
Wanderers: Ingram, Arnold, Dunne, Stewart, Hause, Bloomfield (Kretzschmar 68), Lewis, Scowen, Cowan-Hal (Pittman 76), Knott, Kuffour (McClure 62).
Subs: Horlock, McCoy, Doherty, Spring.
Rovers: Mildenhall, Smith, Packwood, Parkes, Lockyer, Harrison (Harding 79), Clucas (Santos 84), O'Toole, Clarke, Clarkson, Brunt (Henshall 62).
Subs: Gough, Norburn, Keary, Southway.
Attendance: 5,783 (345 Wycombe)