Roger Federer and Stanislas Wawrinka won their singles matches on Friday to give Switzerland a convincing 2-0 lead over Serbia in their World Group first-round tie. Returning to Davis Cup tennis, Federer cruised past Ilija Bozoljac, winning 6-4, 7-5, 6-2 in less than two hours. Australian Open champion Wawrinka faced a tougher task against 102-ranked Dusan Lajovic in the second match, before winning 6-4, 4-6, 6-1, 7-6 (7).