Rio de Janeiro: The US pair of Bethanie Mattek-Sands and Jack Sock beat compatriots Venus Williams and Rajeev Ram for the gold medal in the tennis mixed doubles at the ongoing Rio Olympics here. Mattek-Sands and Sock lost the first set 6-7 (3) but neatly won the second set 6-1 and the third set 10-7 in a super tiebreak at Rio's Olympic Tennis Center on Sunday, reports Efe. Mattek-Sands, 31, who just two months ago had broken her left thumb, and Sock, 23, who also won a bronze medal in Rio in doubles play, had triumphed over the Czech team of Lucie Hradecka and Radek Stepanek in the semifinals The Czechs won the bronze medal on Sunday by defeating India's Sania Mirza and Rohan Bopanna 6-1 and 7-5. The win by Mattek-Sands and Sock prevented Williams from becoming the first tennis player in history to win five Olympic golds, although her silver ties her at five medals of whatever type with Britain's Kathleen McKane, who won her awards in 1920 and 1924. Although both pairs broke each other's serves in the first set, Ram came through at the net during the tiebreak and Mattek-Sands and Sock dominated in the second set, going out to a 5-0 lead but ultimately prevailing, despite conceding one game. The third set resulted in an exciting 10-point match tiebreak, with Mattek-Sands and Sock going out in front 3-0 to start but then temporarily crumbling to 3-6 before battling back to 8-6 and finally widening the lead to the 10-7 result. Venus Williams had been eliminated in women's singles in the first round, although she had won the event in Sydney in 2000, along with the doubles there, and secured the gold at both the 2008 Beijing and 2012 London Games.