Croatia began the defence of their Davis Cup title with a 3-0 defeat by Group B rivals Russia as the new-look tournament got under way in Madrid.
Borna Gojo was beaten 6-3 6-3 by Andrey Rublev and Borna Coric went down 6-7 (4-7) 6-4 6-4 to Karen Khachanov before the Russian pair combined to win the final doubles match.Russia face Spain on Tuesday.
In Group F, Canada's Vasek Pospisil and Denis Shapovalov both won as they secured a 2-1 win over Italy.
World number 150 Pospisil beat world number 12 Fabio Fognini 7-6 (7-5) 7-5 and Shapovalov battled past Matteo Berrettini, fresh from his ATP Finals debut, 7-6 (7-5) 6-7 (3-7) 7-6 (7-5). The Italian pair then defeated the Canadian duo in the final doubles contest.
And in Group D, Steve Darcis and David Goffin both won their singles matches as Belgium recorded a 2-1 win over Colombia.