Mario Vrančić's 90th-minute free-kick condemned the Wanderers to a harsh defeat after a strong display against Norwich City at Carrow Road on Saturday afternoon.
In a lively opening, Norwich and Wycombe traded goals within the first 12 minutes through Teemu Pukki and Scott Kashket. The Norwich striker opened the scoring early on but Kashket drew the sides level after a long ball from Joe Jacobson was headed down by David Wheeler, and the Wycombe striker slot the ball home.
Wycombe controlled the rest of the first half, coming close with headers by Anthony Stewart and the goal-scorer Kashket. The second half was a more even matchup, as Norwich grew into the game, calling Ryan Allsop into action a few times.
The team news ahead of the game revealed two changes to the line-up that Ainsworth chose against Reading. David Wheeler and Fred Onyedinma found their places in the starting eleven, replacing Matt Bloomfield and Alex Samuel. Uche Ikpeazu returned to the bench.
The first chance of the game was the first goal of the game as Teemu Pukki was played in behind the Chairboys' defence. The Finnish international lofted the ball over Ryan Allsop into the left-hand side of the goal.
Norwich were firmly in control as they came close after a quick passing move between Todd Cantwell, Emi Buendía and Pukki, but only a corner came from a tame shot.
After a strong opening from Norwich in the attack, they showed complacency in defence as Scott Kashket levelled the score. The goal came from a long ball up to Wheeler who nodded it down to Kashket. Norwich failed to deal with the Wycombe striker who tapped the ball in from close range.
Minutes later, Wycombe appealed for a penalty as Ben Gibson brought down Onyedinma, but the referee ignored the protests. Replays showed clear contact, with the Norwich defender's arm on Onyedinma's back.
Wycombe dictated the rest of the first half, playing good football and creating decent chances including an Anthony Stewart header that went just over the bar.
Kashket nearly doubled his tally before the break, but he put the header into the side netting after a cross to the back post from Daryl Horgan. The Chairboys finished the half level, having shown great resilience to turn the game around after a very strong start from the Canaries.
The second half opened with an early chance for Wycombe as Jacobson nearly scored directly from a corner. Norwich keeper Tim Krul failed to deal with the ball in, but Grant Hanley cleared it off the line.
Lukas Rupp came close for the home side later on, but Anthony Stewart jumped in-front of a shot that looked destined for the back of the net.
Norwich substitute Adam Idah forced a good save out of Allsop, after managing to create space for a shot just inside of the box 60 minutes in.
Wycombe weren't far away from taking the lead through Onyedinma, who curled an effort to the far post and just missed by a few inches.
As the game entered the closing stages, Norwich started to find more opportunities but Allsop stood strong, make good saves after shots from Cantwell and scorer Pukki.
However, on 90 minutes Norwich won a free-kick and Vrančić curled a great strike into the top right-hand corner to win the game for the home side. In an off-the-ball incident, Adam Idah was given a straight red card for coming together with Jacobson.
Ainsworth's side dug-in and battled against a good Norwich side, but couldn't quite hold on and will instead turn their attention towards Watford at Adams Park on Tuesday.