"It's a big punch to the face," Arsenal manager Mikel Arteta said after Saturday's defeat.
"Now it's about how we react to that, because it's game on, it's going to require now a big spirit, a lot of fight."
Alex Scott was Bournemouth's 74th-minute matchwinner at the Emirates, piling pressure on Arsenal ahead of next week's top-of-the-table clash at Manchester City.
Arsenal have played two more games than City, who travel to Chelsea on Sunday and could close the gap to six.
Arsenal haven't won the title since 2004 and are slumping at the worst time, defeats to City in the League Cup final and to second-division Southampton in the FA Cup having ended their pursuit of a quadruple of trophies.
They beat Sporting Lisbon 1-0 in the Champions League on Tuesday but the latest loss will only heighten tension in the race for the title after three-straight years of being runners-up.
"The fact that as a club we haven't done it for so long, there's a reason for that, it talks about the difficulty," Arteta said.
Bournemouth went ahead inside 17 minutes through Junior Kroupi's close-range goal.
Viktor Gyokeres levelled from the penalty spot in the 35th but Arsenal struggled to create openings and Scott sealed the victory that potentially blew the title race open.
Elsewhere, Liverpool got a glimpse of the future as 17-year-old Rio Ngumoha scored a brilliant solo goal in a 2-0 win against Fulham.
The forward curled in the opening goal at Anfield, while Mohamed Salah added the second in his first game in front his home fans since announcing he was leaving Liverpool at the end of the season.
Ngumoha announced himself early in the season with his dramatic late winner against Newcastle and he produced another special moment with his first Anfield goal.
Liverpool tightened their grip on fifth place and Champions League qualification, moving four points clear of Chelsea in sixth.
Kiernan Dewsbury-Hall struck in stoppage time as Everton twice fought back from a goal down to draw at Brentford 2-2. Igor Thiago had twice given the hosts the lead.
Mats Wieffer scored in both halves as Brighton beat Burnley 2-0.
