Eddie Howe refused to blame his Bournemouth team's midweek FA Cup exploits or the weather for the Cherries' defeat at Walsall.
Howe lost his first game since returning as manager at home to Wigan in a third-round replay on Tuesday night and suffered his first league loss at the Banks's Stadium.
The 10-man Saddlers halted the Cherries' 15-game unbeaten league run and completed the double over the south coast club after a 2-1 victory at Dean Court back in September
Howe said: "We never really showed our true colours, but it was a strange game and we had enough chances to score three or four goals.
"It's something we have got to get over quickly and hopefully this was a one-off. If we had defended well we would have won the game.
"The pitch was heavy but no problem. They made a great effort to get the game on."
A 27th-minute strike by Sam Mantom and a Will Grigg penalty on the stroke of half-time gave Walsall a 2-0 advantage.
Brett Pitman pulled a goal back with a header four minutes into the second half and Wes Thomas hit the crossbar for the Cherries before Saddlers striker Febian Brandy was sent off for a second bookable offence after 72 minutes to give Bournemouth a great chance of saving the game.
But a bizarre incident in the 79th minute, when Eunan O'Kane picked the ball up in the area mistakenly thinking Walsall had been awarded a free-kick, handed the home side a second penalty which Grigg duly dispatched for his 10th goal of the season.