The tie will now go down to the final day , with Cilic to try and keep the matchup alive against Isner in Sunday 's reverse singles .
Sock and Coric could potentially contest the decisive fifth rubber .
The tie will now go down to the final day , with Cilic to try and keep the matchup alive against Isner in Sunday 's reverse singles , while Sock and Coric could potentially contest the decisive fifth rubber .