The 23-year-old Dutch under-21 international joined Sunderland from NEC Nijmegen last July and has kept 10 clean sheets in 33 Premier League appearances, helping the newly promoted club establish themselves comfortably in mid-table in their first top-flight season in years.
Chelsea's interest is driven by persistent uncertainty over their current options in goal. Robert Sanchez has delivered inconsistent performances throughout a turbulent season, and Filip Jørgensen has not convinced as an alternative. Incoming head coach Xabi Alonso is expected to demand a reliable first-choice keeper as one of his earliest priorities.
Liverpool's pursuit is tied to the potential departure of Alisson Becker, who has attracted interest from Juventus and several Italian clubs. Deputy Giorgi Mamardashvili, signed last summer as the intended long-term successor, has yet to demonstrate he is ready to take on that responsibility full-time.
Sunderland hold significant contractual leverage, with Roefs tied to the club until 2030. They are expected to demand a fee in the region of 50 million pounds before considering a sale.
NEC Nijmegen are also entitled to approximately 10 percent of any profit made on a future sale under the terms of last summer's transfer, meaning their former club could receive a windfall of several million pounds if a deal of this scale goes through.
Liverpool are understood to be moving quickly to get ahead of Chelsea's interest, with sources describing their pursuit as concrete and strengthening.