* Napoli twice came back only to lose 3-2 to Besiktas
* Aboubakar's double included late headed winner
* Besiktas goals all came from poor Napoli defending
* Insigne missed a penalty for Napoli early in the second half
* Second Napoli penalty converted by substitute Gabbiadini
* Besiktas host Napoli in next round of matches
MILAN, Oct 19 (Reuters) - Vincent Aboubakar headed a late goal, his second of the game, to give Besiktas a shock 3-2 win away at Napoli in the Champions League after the Serie A team had twice come from behind and missed a penalty along the way.
An early goal by Adriano gave Besiktas the lead, Dries Mertens equalised on the half hour and Aboubakar put the Turkish side back in front before halftime in the Group B game.
Lorenzo Insigne's penalty was saved by Fabricio in the 50th minute but Napoli were awarded another spot kick 19 minutes later and substitute Manolo Gabbiadini converted.
Gabbiadini also had a goal disallowed for offside before Aboubakar got behind the Napoli defence to head home in the 86th minute, leaving Napoli with six points in Group B and the Turkish side with five. (Writing by Brian Homewood; Editing by Ian Chadband)