Melbourne, Jan 29 (IANS): India's Leander Paes could not add to his six mixed doubles Grand Slam titles as he and his Russian partner Elena Vesnina lost the Australian Open final to eighth seeds Bethanie Mattek-Sands and Horia Tecau in the super tie-break here Sunday.

Paes and Vesnina hit 14 unforced errors to their opponents' 20, but the American-Romanian combine smashed 34 winners which in the end made all the difference.

The Indo-Russian lost the first set. But they came back strongly to take the second. However, in the super tie-break they coudn't get the better of their opponents and lost 3-6, 7-5, 3-10.

Paes, 38, struggled with his serve while the American Bethanie was flawless in returning. The No.5 seeds also failed to capitalise on the seven break points on offer, converting only three.

India's tennis veteran had won the men's doubles title with Czech partner Radek Stepanek here Saturday for the first time ever to become the first Indian to complete a career Grand Slam.

Paes won the mixed doubles title here in 2003 and 2010 with American great Martina Navratilova and Zimbabwe's Cara Black.

The Indian has reached 13 Grand Slam finals. His most successful partner has been Black, with whom he won the 2008 US Open, 2010 Wimbledon and Australian Open.