Adelaide United defender Daniel Mullen is on the verge of signing with a Chinese soccer club.The 22-year-old will join Super League club Dalian Aerbin for an undisclosed fee, if he passes a medical examination within days."Dalian Aerbin came to us with a substantial fee for Daniel and he expressed his desire to head to China," Adelaide United's football director Michael Petrillo said in a statement on Monday."It was a decision we did not take lightly because Daniel is an integral part of our squad."Mullen, expected to sign a two-year deal with the Chinese club, played 79 games for Adelaide, his hometown club.