Sept 25 (Reuters) - The doubles pairing of American John Isner and Denis Shapovalov of Canada notched up the first win for Team World in the Laver Cup in Boston on Friday with Team Europe heading into the weekend with a 3-1 lead after the opening day. Isner and Shapovalov defeated German Alexander Zverev and Italian Matteo Berrettini 4-6 7-6(2) 10-1 in the final match, bringing the TD Garden crowd to their feet with the clock minutes away from striking midnight. Named after Australian great Rod Laver, the three-day team event pits six of Europe"s top players against six of their counterparts from the rest of the world with four matches played each day (three singles and a doubles). Each match win is awarded one point on Friday, two points on Saturday, and three points on Sunday with the first team to reach 13 points declared winner of the event, which was cancelled last year due to the COVID-19 pandemic. Team Europe have won all three editions of the Laver Cup so far and they did not seem perturbed by the absence of Roger Federer, Rafa Nadal and Novak Djokovic in their ranks for this year"s tournament when they jumped to a 3-0 lead in the singles. The crowd at the indoor arena, used by the NBA"s Celtics and NHL"s Bruins, were fully behind Team World but their vociferous support was not enough to derail Norway"s world number 10 Casper Ruud against big-serving American Reilly Opelka. With Federer watching from the stands, Ruud neutralised his opponent"s booming serves on the hardcourt to win 6-3 7-6(4) as the six feet 11 inches tall Opelka described it as the "slowest condition I have ever played in". Swiss Federer, who is a co-creator of the exhibition event, is recuperating from a knee surgery he underwent last month but thrilled the Boston crowd by making a surprise trip. "I got a text from Stefanos (Tsitsipas) saying where I am, he"s missing me and he needs me on the team," Federer, who received a warm applause from the spectators at TD Garden, said ahead of the start of the tournament. "I didn"t tell him yet I am coming, so that"d be a surprise." With the deciding third set a 10-point match tiebreaker at the Laver Cup, Wimbledon finalist Berrettini saved 12 of the 13 breakpoints he faced against Canadian Felix Auger-Aliassime to rally to a 6-7(3) 7-5 (10-8) win after a two hour and 52-minute battle against his close friend. Russian world number five Andrey Rublev also had to come back from a set down to beat Diego Schwartzman of Argentina 4-6 6-3 (11-9) as his team swept the singles for a 3-0 lead. Isner will be back for more doubles duty on Saturday when he teams up with Australian Nick Kyrgios against third-ranked Greek Tsitsipas and Rublev. Isner will also play singles against Zverev while Kyrgios faces Tsitsipas. U.S. Open champion Daniil Medvedev of Russia will play the other singles match on the second day against Shapovalov.