Olivier Giroud is on the sidelines with an ankle injury, while back-up forward Nicklas Bendtner has just incurred his own version of an ankle sprain after scoring a crucial 88th minute goal in their win against Cardiff City on Wednesday.
According to reports, Bendtner's recovery period will have to be six weeks at the minimum.
The circumstances create a perfect recipe for Gunners boss Arsene Wenger to seek for an abled striker for the crucial second-half of the season as team standings are closer than ever.
Manchester City are just a point behind the front-running Gunners, while Chelsea only needs 2 points to tie. Liverpool, Everton, and Tottenham are just within striking distance.
The Brazilian, however, will not come in cheap as Arsenal will have to shell out, at least, £32 million - Costa's buyout price. But, with Arsenal in the best position of winning the domestic title this season after several years, a leap of faith to sustain their form throughout the campaign is an option that may be too valuable to pass up.