Norway, who are in the World Group playoffs for the first time since 1995, took a 2-0 lead over Uzbekistan after Ruud beat the lowly-ranked Sultanov in just over an hour, while Viktor Durasovic sealed a 6-4 6-4 win over Denis Istomin.
The teams playing in World Group I are bidding for a place in the 2022 Davis Cup qualifiers, a step closer to the Finals.
It was a breakthrough week for the 22-year-old Ruud, who became Norway’s first player to make it into the world’s top 10.
“It is probably the best week of my life as rankings-wise I have reached a big goal of my career,” Ruud told the Davis Cup website.
“This really is the perfect week for me to play Davis Cup here. Playing for my country is always special and playing at home is something I enjoy doing.
“The ultimate goal for every team is to reach the Finals. Norway has not been to the top of the competition before, but it is something we are fighting for every time we play. It is something which motivates me.”
Elsewhere, South Korea took a 2-0 lead against New Zealand, while Chile and Slovakia were tied 1-1. Finland lead India 2-0, while Peru and Bosnia and Herzegovina were tied 1-1.
There are 12 World Group I matchups in this playoff round, two of which were played in March.
As part of the move from an 18-team Davis Cup Finals to a 16-team event in 2022, only the top eight highest-ranked winning teams from this round will progress to the 2022 qualifiers.
The remaining four teams will play World Group I knock-outs in November, with the two winners then advancing to 2022 qualifiers.
(Reporting by Manasi Pathak in Bengaluru; editing by Richard Pullin)