The Reds are reportedly chasing out of contract Brentford defender Alfie Mawson, but face competition from elsewhere.
The 21-year-old was part of the Wycombe Wanderers side who fell at the final hurdle, missing out on penalties in last season's League Two playoff final against Southend United. He appeared in all but one league game last term, scoring six goals.
He also scooped the Players' Player of the Year and the Supporters' Player of the Year awards after an impressive season at Adams Park.
He graduated through the Brentford academy as a 17-year-old and has spent time out on loan with Maidenhead United, Luton Town and Welling United, before last season's spell with Wycombe.
Radio Sheffield reporter Andy Giddings tweeted this morning about Mawson:
Understand #barnsleyfc are one of 4 clubs trying to sign Brentford defender Alfie Mawson. Bradford, Millwall, Swindon are the others.
I'm told Brentford's Alife Mawson will make a decision on his future in the next 2 weeks. #barnsleyfc #bcafc #Millwall #stfc