Pierre-Emerick Aubameyang
Aubameyang is being scouted by Arsenal this summerReuters

Arsenal are preparing a €40m (£28m, $45m) deal for Borussia Dortmund striker Pierre-Emerick Aubameyang this summer, according to Germany's Bild.

The Gunners are in the market for a striker and have earmarked Aubameyang as the man to add the goal scoring threat to their attack. He was the highest scorer last season for Dortmund in the league, with 25 in all competitions and will be a good acquisition for the club, which is desperate to end their decade-long wait for a league title.

Aubameyang is the fastest sprinter in the Bundesliga and with Theo Walcott, Danny Welbeck and Alexis Sanchez already on board for the Gunners, their frontline will arguably be the fastest in Europe.

Aubameyang scored the second goal in Arsenal's 2-0 loss to Dortmund at the Emirates in September 2014 in the Champions League, which helped the Germans win the group. Chelsea and Manchester City are also believed to be interested in his services.

The Gunners are looking for someone who would provide a different option to Giroud, who doesn't have the pace to run beyond opposition defences. Walcott offers that option but lacks physicality, which makes it difficult for him to link up play around the penalty box.

Aubameyang's arrival will provide Arsenal with a player who can combine the traits of Giroud and Walcott, something which can be exploited by Mesut Ozil and Aaron Ramsey.

Chelsea are also looking for a striker as a back-up for Diego Costa, who suffered multiple injuries last season and was unavailable for major matches in the second half of the season.

Loic Remy put in a good shift in his absencebut was also injured, leaving Mourinho to think over his attacking options. Radamel Falcao has been linked with a move to Stamford Bridge, but his current form for Colombia has raised concerns over his long term future.