San Jose had a golden opportunity to win late in regulation but failed to convert on a full two-minute 5-on-3, even against a back-up goalie, Jonas Hiller, who was forced to enter the game with just three minutes remaining when starter Karri Ramo injured his left leg. [...] rookie defenseman Dylan DeMelo scored his second of the season as San Jose converted a third power play in six chances at 5:55 for a 5-4 lead. [...] Calgary defenseman Kris Russell crashed the net to punch home his fourth of the season at 8:08 on the power play. A strong second period that featured the Sharks outshooting the penalty-plagued Flames 9-4 enabled the hosts to cut their deficit to a goal thanks to two power-play strikes. Couture scored his fifth of the season seconds into the middle period, taking a cross-ice feed from defenseman Brent Burns and beating Ramo with a wrist shot from the left circle. San Jose had another power play before the period expired, but failed to gain the equalizer as Thornton hit the post with a drive. Giordano’s 13th goal snapped an 11-for-11 run by the Sharks’ penalty kill over five games.