Their campaign starts tonight against fellow Kiwi Ben McLachlan - who plays for Japan - and German Jan Lennard Struff. It's a repeat of last week's Japan Open final won by McLachlan and Struff in straight sets.
This evening's match against McLachlan and Struff is important, because that duo is 11th in the race and a big run in Shanghai could put them in touching distance of Klaasen and Venus. Throw in the uncertainty around Venus' playing schedule with him about to become a father and qualifying for London is not straightforward.
Venus is scheduled to have next week off before playing the ATP 500 tournament in Basel and the Paris Masters 1000, the final event before the World Tour Finals.
Last year, Venus and American Ryan Harrison made the semifinals in London after going through round robin group play unbeaten. It's a lucrative tournament to play in with team's receiving $154,370 just for participating, $58660 for each round robin win, $159,000 for winning a semi-final, $308,740 for winning the tournament and going through unbeaten $798,092.
Meanwhile the second Kiwi in the Shanghai field, Artem Sitak, has lost his second round doubles match with Indian partner Divij Sharan 6-3 6-4 to third seeds Lukasz Kubot and Marcelo Melo.