That is why they have decided to play just with each other this year so they have the same ranking (they hope # 1) at the end of the year. Judging from the WTA Player Guide the Olympics is not giving ranking points for doubles, so it won't harm them to play there.
Mirjana Lucic : Australian Open doubles champ and back in Top 100
Jelena Jankovic : US Open finalist 2008 and World No. 1
Jennifer Capriati : 3 Grand Slams, Olympic Gold and World No.1
[center]Rafael Nadal : 10 Grand Slams, Olympic Gold and World No.1 [/center]