Stephens into Charleston final as ill Kerber quits

American seventh seed Sloane Stephens reached the final of the Charleston clay court tournament on Saturday when Australian Open champion Angelique Kerber was forced to quit their semifinal.

Top seed Kerber of Germany was understood to be suffering a viral illness before retiring at 6-1, 3-0 down.

Stephens, with titles in Auckland and Acapulco already in 2016, will face either Italian fifth seed Sara Errani or Russian qualifier Elena Vesnina in Sunday's final.

"I wish Angie a speedy recovery, she's a great girl — I'm happy to be in the final though," said Stephens.

Elena Vesnina sealed her place in the decider with a surprise 6-4 4-6 6-2 victory over Sara Errani, becoming the first qualifier to reach the final in the tournament's 44-year history. 

The Russian outsider won 65 per cent of points on her first serve and broke six times to set up a showdown with Stephens at the expense of the fifth seed.