Napoli striker Dries Mertens has allegedly emerged as a transfer target for Borussia Dortmund.

As a result of the Belgium international's contract being due to expire at the end of the season, Manchester United are said to be keen on signing the 32-year-old on a free transfer.

However, according to Calciomercato, Dortmund are ready to try to secure a deal for the long-serving Napoli player in January.

After claims that Mertens has rejected the offer of fresh terms at his current club, Dortmund are allegedly prepared to bid in the region of £8.5m.

With Napoli currently sitting well adrift of the top four in Serie A, president Aurelio De Laurentiis will likely weigh up whether cashing in on one of Gennaro Gattuso's key men is worth the risk at this stage of the campaign.

Mertens has contributed nine goals and three assists in Italy's top flight and the Champions League this season.