Claude Giroux scored the go-ahead goal in the second period and the visiting Ottawa Senators defeated the Toronto Maple Leafs 4-2 on Saturday night. Jake Sanderson, David Perron and Michael Amadio also scored for the Senators, who have won six in a row and won their past five games against the Maple Leafs -- three this season. Linus Ullmark stopped 21 shots. William Nylander and Auston Matthews scored for the Maple Leafs, who have lost five of six. Anthony Stolarz made 21 saves. The Senators had the early energy in the first period, were effective in transition, and Stolarz was the first goaltender to be tested. Ottawa had a 10-5 advantage in shots on goal in the first, which was indicative of the flow of the game. Ottawa took a 3-2 lead in a five-goal second period. Toronto started the second with more verve and John Tavares had his 22-foot shot from the right circle ring off the crossbar at 1:33 following an Ottawa turnover. After a poor Ottawa line change, Nylander finished a smart individual effort by stuffing home a six-foot backhand at 6:49. Ottawa answered with a surge that was rewarded with Sanderson's goal on a shot from the left circle at 7:57. Toronto regained the lead when Ullmark mishandled the puck in front of the net between the hash marks, leaving a gift goal on a 39-foot wrist shot for Matthews at 8:55. Ottawa tied the game again on Perron's blast from the left circle at 12:16 following sloppy Toronto defensive play. Ottawa took the lead for the first time at 14:08 with Giroux's power-play goal on a shot that deflected off Toronto defenseman Christopher Tanev into the net. Oliver Eckman-Larsson was off for interference. The Senators used an effective fore-checking game to open the third period that kept the Maple Leafs bottled up. Toronto picked up the urgency midway through the third and had a few better looks at the goal. Toronto went on the power play at 14:51 of the third. Ottawa had the best chance, however, but Giroux was foiled on a breakaway. Amadio scored into an empty net at 19:53.