Oct 17 (Reuters) - The Chicago Sky came from behind to beat the Phoenix Mercury 80-74 and win the best-of-five finals series 3-1 on Sunday, earning the franchise its first championship. The Mercury looked poised to force a Game Five when they took a 14-point lead late in the third quarter but the Sky came roaring back, tying the game at 72 in the fourth quarter on a wide open three pointer by Candace Parker. The Sky took a lead they would not relinquish on back-to-back buckets by Stefanie Dolson and played lock-down defense on the final Mercury possessions to win the title and send the sold-out Chicago crowd into a frenzy. Allie Quigley scored 26 points and fellow guard and wife Courtney Vandersloot came one rebound away from a triple-double as the Sky won behind a balanced attack they have been riding all postseason. "I"m so proud of this group," said Parker, who finished with 16 points, 13 rebounds and four steals to win her second championship. "So proud of our fight, of our next man up mentality. Stef coming in and having those two layups, Sloot doing what she"s done all year. Allie too. It"s amazing. "We"ve got the whole city here. It"s amazing how Chicago supports us. We"re champions for life now." The Mercury, who were blown out in Game Three, were much better through the first three quarters. The visitors finished the first half on a 9-0 run to take a 44-37 lead into the break and led 63-54 at the end of the third quarter behind dominant post play by Brittney Griner, who finished with a game high 28 points. But the fourth quarter belonged to the Sky, who outscored the Mercury 26-11 in the final period to bring the trophy to Chicago.