BRUSSELS - Leonardo Mayer and Carlos Berlocq gave Argentina a 2-1 lead over Belgium in their Davis Cup semifinal Saturday after a tense doubles match against Steve Darcis and Ruben Bemelmans that lasted four hours.

Spurred on by the vocal Belgium fans on the hard court at Forest National, Darcis and Bemelmans got off to a sluggish start but saved 16 of 21 break points they faced before the Argentine pair prevailed 6-2, 7-6 (2), 5-7, 7-6 (5).

"It's been four hours, two days, long matches but I have energy," said Mayer, who extended his winning streak in Davis Cup to nine matches. "Davis Cup is like this, and I love playing in Davis Cup."

The Argentines need one more point from Sunday's reverse singles to reach their fifth Davis Cup final after finishing runner-up four times.

Belgium's last appearance in the semifinals ended with a 4-1 loss against France in 1999. The hosts last qualified for the final as far back as 1904.

Both pairs had played just one Davis Cup match together and were announced one hour before the rubber as team captains decided to amend their lineups.

Mayer and Berlocq got off to an excellent start as their lack of common experience did not show. Bemelmans was broken in the opening game and the Argentines remained in control afterwards.

They broke for a 2-1 lead in the second set but Darcis and Bemelmans came back from 5-2 to force a tiebreak in which Mayer and Berlocq won six points in a row to tighten their grip on the match.

The Belgians raised their level in the third and broke once to stay in the match before Darcis saved a match point with a lob and Bemelmans produced two other winners to level at 5-5 in the fourth.

Darcis saved another match point in the final tiebreak with a forehand down the line but sent a return long on the next one on Berlocq's serve.

"The match was really, really close," said Argentine captain Daniel Orsanic. "At the end, Leo and Charly got a little bit loose, they were able to hit the ball cleaner and that made the difference. It was a very exciting match."

In Sunday's reverse singles, Belgium's top player David Goffin will take on Mayer with Darcis scheduled to play against Federico Delbonis in a potentially decisive fifth match.

On Friday, the big-serving Mayer defeated Darcis in four sets to draw Argentina level at 1-1 after David Goffin had put the hosts ahead with a 7-5, 7-6 (3), 6-3 defeat of Federico Delbonis 7-5, 7-6 (3), 6-3.