Defending champion Roger Federer reached the Australian Open third round for a 20th straight year Wednesday but was made to battle all the way by Britain’s Dan Evans before winning 7-6 (7/5), 7-6 (7/3), 6-3. The ageless 20-time Grand Slam champion, who is going for a record seventh Melbourne Park title and third in a row, had breezed past Denis Istomin in the first round, but was given a much tougher examination by the world number 189. The 37-year-old Swiss master will play either France’s Gael Monfils, seeded 30, or American Taylor Fritz in the last 32.