Ekaterina Makarova is currently World Doubles No.1 - but the only way for her to stay in the top spot is to win the Wimbledon title.
She and Elena Vesnina are currently co-No.1s, and will have notched up five weeks on top of the rankings by the end of Wimbledon.
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But the Russian pair are not playing together this time round, with Vesnina not competing at all - and so Makarova will need to lift the trophy with partner Vera Zvonareva in order to maintain her position.
Makarova and Vesnina are the 13th pair to hold the co-No.1 status, and the second and third from their country to reach the top spot in the WTA doubles rankings, following Anna Kournikova's achievement on November 2, 1999.
At the time, Makarova described it as "such an honor to be the WTA World No.1 doubles players", with Vesnina adding that it was "what we've always dreamed of."
Timea Babos is the frontrunner to take the top spot; she competes with partner Kristina Mladenovic at SW19.
Latisha Chan has a chance of returning to World No.1 - but she needs to reach the semifinals with partner Peng Shuai in order to do so.
She would also need Makarova not to win the title - and hope that Andrea Sestini Hlavackova can't manage it either.
Hlavackova can become World No.1 if she does win the title with her partner Barbora Strycova - as long as Chan doesn't reach the final, and Timea Babos does not reach the semifinals.
