Troy Deeney scored twice to put visitors Watford 2-0 up before four goals in six remarkable minutes shook up the scoreline. 

First, goals from Nathan Ake and Callum Wilson pulled the Cherries level, although they were soon behind once again when Ken Sema drilled home. 

Ryan Fraser then levelled matters for a second time before the nets were given a rest in a goalless second half.

Watford went in front after 14 minutes, when some neat play down the right led to a cross from Sema that found Deeney in space, the striker planting a powerful header beyond goalkeeper Asmir Begovic. 

Deeney doubled his tally when Steve Cook's challenge to halt a Gerard Deulofeu run inadvertently rolled the ball into the Watford captain's path, leaving him to slot past Begovic. 

The away side should arguably have been reduced to 10 men soon after, Abdoulaye Doucoure escaping with a yellow card following a studs-up challenge on Fraser. 

Ake then pulled the home side back into the match, reacting quickest to nod home after Ben Foster produced a brilliant save to deny Dan Gosling, and Wilson's looping header had them level three minutes later. 

A staggering period of play then saw Sema fizz a left-footed strike into the bottom right-hand corner to restore Watford's lead after Bournemouth failed to clear a long ball, before Fraser got on the end of a Junior Stanislas pass from the right wing to make it 3-3. 

Doucoure was replaced in the 56th minute after looking in danger of upgrading to a red card, although Etienne Capoue was then lucky to avoid a second yellow after catching Gosling with an arm to the face. 

Foster - impressive despite conceding three goals - superbly pushed over a Wilson header and was again on hand to prevent Josh King capitalising on a Craig Cathcart error in the box 15 minutes from time.

Ake survived Watford calls for a penalty after the ball struck his arm in stoppage time, as a game of vastly contrasting halves neared a climax.