Fernando Verdasco beat Xavier Malisse 6-4, 6-3, 6-1 to give Spain a 1-0 lead against Belgium in a Davis Cup World Group tie on Friday.
Top-ranked Rafael Nadal was to play Ruben Bemelmans in the second match on a hard-court in southern Charleroi.
Verdasco was put in at the last moment after David Ferrer pulled out of the opening match with an inflamed nerve in his shoulder.
He was still too much to handle for Malisse, drawing the Belgian into long rallies he'd invariably win.
Despite suspecting he would be called in as a substitute since late Thursday, Verdasco suffered some early jitters, with Malisse quickly threatening to take his serve. Verdasco hung on.
"The beginning of the match was the key. You get the confidence," Verdasco said.
From then on he took charge behind his powerful serve. Even if Malisse won the most spectacular points, he also was the sloppiest with his unforced errors.
After Belgium accidentally laid down a hard-court far too slow for its taste, it also found the 6,500-Spiroudome less of a home-court advantage because of hundreds of cheering and celebrating Spanish fans.
"It was not as fast as we thought it would be," said Verdasco.
Doubles is set for Saturday and reverse singles for Sunday. In 2003, Spain beat Belgium 5-0.