Tuesday was a mixed day for the Germans in Stanford, Angelique Kerber beating Daria Gavrilova in straight sets while Sabine Lisicki went out to Japanese veteran Kimiko Date-Krumm.

Kerber strolls through 

Kerber had no problem overcoming her Russian opponent, winning 61 63 in just 65 minutes. The German broke her 21-year old opponent five times, and won 54% of points on return. Despite having won three titles so far this year, Kerber has been disappointing in 2015's biggest events - she's failed to reach the last 16 at any of the first three majors. She's a former US Open semifinalist though, and will be looking for hard court wins as we build to New York - she's just 8-9 on the surface in 2015.

Gavrilova has had some good results this year, most notably reaching the semifinals in Rome, and at 41, is close to her career high ranking of 39. This however, was her third loss in a row, a run of form she'll hope to turn around before the US Open later this month.

But Lisicki could not follow her compatriot into the second round, going down 16 76 62 to 44-year-old Date-Krumm. Lisicki continued her inconsistencies on serve, hitting eight aces but also six double faults in a match featuring ten breaks of serve.

And Date-Krumm will be delighted to get her first win on the main WTA tour in 2015, against a player almost 150 places above her in the rankings. For Lisicki, it's another loss in an up-and-down season featuring a semifinal in Indian Wells and a quarterfinal in Miami, but a win-loss record of just 17-17.

Kerber goes on to face Croatian 17-year-old Ana Konjuh in round two, in what will be the first meeting between the players. Konjuh won her first WTA title in Nottingham in June, and will be looking to regain lost ground in the rankings after an early loss at Wimbledon.

Date-Krumm will play world number 11 and fourth seed Karolina Pliskova for a place in the third round.