LONDON — Britain reached the Davis Cup final for the first time in 37 years Sunday as Andy Murray outclassed Australia's Bernard Tomic in straight sets to give it an unbeatable 3-1 lead. World No. 3 Murray had teamed up with brother Jamie to win a thrilling five-set doubles rubber against Lleyton Hewitt and Sam Groth Saturday to leave the host needing to win just one of Sunday's reverse singles. The 28-year-old, who became the first Briton to win the Wimbledon men's singles in 77 years in 2013, duly delivered his third point of the match, beating an increasingly dispirited Tomic 7-5, 6-3, 6-2 to wild cheers from a partisan Glasgow crowd. In doing so, and setting up a final away to Belgium, Murray improved his record in Davis Cup singles to 25-2 — an impressive contribution and the main reason Britain have risen from the depths of the competition in 2010 to within one victory of their first title since 1936. Australia captain Wally Masur said Murray had been the difference between the sides. Murray will need to summon one final effort at the end of the season when Britain will face Belgium, probably in Brussels, on Nov. 27-29 after it edged past Argentina 3-2 Sunday. Steve Darcis sent Belgium into its first Davis Cup final in more than a century by beating Federico Delbonis in the decisive fifth match against Argentina. Darcis, who lost his opening singles match and was defeated in doubles Saturday as Argentina built a 2-1 lead, finally grabbed a point with a 6-4, 2-6, 7-5, 7-6 (3) win in a deafening atmosphere at the Forest National. Earlier, Belgium's No. 1 player David Goffin defeated Diego Schwartzman to draw Belgium level. In the playoffs, where the winners will feature in the elite World Group in 2016, Roger Federer defeated Thiemo de Bakker 6-3, 6-2, 6-4 as Switzerland wrapped up victory over the Netherlands in Geneva. But Federer, 34, who led Switzerland to a first Davis Cup title in 2014, then hinted that Sunday may have been his last appearance in the tournament. In Tashkent, Jack Sock defeated Denis Istomin 6-2, 2-6, 6-4, 6-4 to give 32-time champion United States victory over Uzbekistan. The Czech Republic, champion in 2012 and 2013, saw off India in sweltering New Delhi when Jiri Vesely thrashed Yuki Bhambri 6-3, 7-5, 6-2. Italy also preserved its World Group status when world No. 28 Fabio Fognini defeated Teymuraz Gabashvili 7-6 (7-4), 6-3, 7-6 (7-5) to secure victory against Russia in Irkutsk. In Gydnia, Poland clinched a World Group spot for the first time when Michal Przysiezny defeated Slovakia's Norbert Gombos in the deciding fifth rubber, 6-3, 6-4, 6-4. — Agencies