Napoli paid the price for poor finishing and Pepe Reina errors as they suffered a shock 2-1 Champions League defeat at Shakhtar Donetsk.
Elsewhere in the group, Manchester City earned a commanding 4-0 victory away to Feyenoord.
The Partenopei rested Dries Mertens in favour of Arkadiusz Milik, who bagged a brace in Ukraine a year ago against Dynamo Kiev. Maurizio Sarri’s men had won their last 10 competitive games in a row and reached the group phase by crushing Nice 4-0 on aggregate in the play-offs. Shakhtar missed defender Serhiy Krystov with a fractured kneecap, but relied heavily on their Brazilian contingent.
Taison and Milik drilled just wide, but Shakhtar took the lead with a well-worked move. Facundo Ferreyra flicked on a Darijo Srna low ball and Taison took it first time from the edge of the box, firing into the near bottom corner.
Napoli had also fallen behind in Ukraine last year, but went on to win 2-1. However, it was almost 2-0 for Taison moments later, Reina rushing out to block with his legs.
Raul Albiol nodded a corner over at the back post, while Ismaily intercepted a great Insigne cross with Milik waiting to tap in.
Napoli put together a series of corners and Insigne’s free kick was simple enough for Andriy Pyatov, while Ismaily’s attempted block on a Faouzi Ghoulam cross almost flew into his own net.
Milik was incorrectly flagged offside on 40 minutes, but had poked straight at the goalkeeper anyway.
Insigne tried one of his trademark curlers on the stroke of half-time, but Pyatov flew to fingertip it out of the far top corner.
Napoli kept far more of the ball in the second half, but were still open on the counter, Facundo Ferreyra turning off target.
The second goal was mainly the fault of Reina, who came off his line and completely missed the cross, allowing Ferreyra to nod in undisturbed at the back post.
Mertens replaced Hamsik and immediately had a chance, controlling Ghoulam’s cross only to see his shot smothered by Pyatov.
The Belgian did contribute to re-opening the game, as he cut inside and was scythed down by Taras Stepanenko for a penalty, which Milik then converted.
Mertens wreaked havoc in the defence, forcing a last-gasp tackle for a corner, then Mertens and Insigne had shots charged down in the box, while Reina saw a Fred strike bounce off his chest.
Shakhtar almost added a third from a set play, Ferreyra’s header bouncing off the upright and Kovalenko just prodding the rebound into a grateful Reina’s arms.
Moments later, Milik fired over the bar from a very promising position, then Darijo Srna shanked his finish when unmarked.
A floated pass found Callejon for a side-foot volley, but Pyatov got the great save and nobody was ready to meet the rebound.
Shakhtar Donetsk 2-1 Napoli
Taison 15 (S), Ferreryra 58 (S), Milik pen 72 (N)
Shakhtar Donetsk: Pyatov; Srna, Ordets (Khocholava 92), Rakitskiy, Ismaily; Stepanenko, Fred; Marlos (Kovalenko 76), Bernard, Taison; Ferreyra (Dentinho 87)
Napoli: Reina; Hysaj, Albiol, Koulibaly, Ghoulam; Zielinski (Allan 67), Diawara, Hamsik (Mertens 60); Callejon, Milik, Insigne
Ref: Zwayer (GER)