Roma coach Claudio Ranieri admits his side are "going through a tough period" after they suffered a heavy home defeat to Serie A rivals Napoli.

Ranieri has lost two of his three games in charge since being re-appointed as Roma boss, this time a 4-1 reverse to their high-flying visitors.

Arkadiusz Milik opened the scoring with a fine second-minute strike, with Roma levelling on the stroke of half-time through Diego Perotti's penalty.

But Napoli pulled clear after the interval as Dries Mertens, Simone Verdi and Amin Younes secured a clear victory for Carlo Ancelotti's men.

Roma now sit sixth in the table and Ranieri conceded it is difficult for him to get a tune out of his squad at present.

"We're doing everything," he told reporters after the game.

"We're going through a period where we concede from the first attack in the first half. We were able to equalise – I don't know how – but they scored the second goal from their first attack after the break.

"It is hard, you try to help the group, but the other team runs more. It's difficult to help them, it is difficult, but we're not giving up. It is hard but we're doing our best."

The win keeps Napoli as the best of rest in Serie A, 10 points clear of Inter Milan in third place but still 15 adrift of leaders Juventus.

Having lost just four league games this season, Ancelotti revealed the victory was nothing more than he anticipated from his players.

"I expected this good performance from the boys," he said.

"We prepared for this match very well, I saw the spirit in the group even in training and I was sure there would be maximum application.

"It was a quality result, although I must say in the first half I did not always like the attitude. It is no coincidence that the first half, despite our dominance, ended 1-1.

"We gave Roma the chance to equalise, then in the second half we re-established the gap that I believe was accurate."