Cahill has been identified by the Gunners as the man to plug their leaking defence, and in light of the Trotters' well documented financial position, Arsene Wenger believes he has a very real chance of signing him.
The centre-back has played a key role in Wanderers march into the Premier League's top five and while manager Owen Coyle would be loathed to lose him, a deal may have to be done if the right offer is made.
Wenger is woefully short of experienced options at the back due to Thomas Vermaelen's long-term injury and his absence is a massive blow for the Frenchman.
Everton's Phil Jagielka had been the Gunners' top target but Wenger has now switched his attentions to Cahill although he wouldn't be prepared to match the Trotters' 18m asking price.
Chelsea could also be in the market for the England international as they seek to reinforce their back-line due to injuries to regular defensive pair Alex and John Terry.