In case you are thinking that the lens you have may not be able to capture "the moment", you may want to consider renting lens from Camera Rental Centre. They are located just opposite Central @ Clark Quay. I've rented a couple of times from them, I find the range of lens, especially for Canon cameras, are pretty good and often they have promotion which you can rent the lens at a good price / rent with free extended days. The staff are pretty well verse in photography and able to answer to my queries when in doubts.
They actually have a F1 promotion right now. Just Flash your F1 ticket and you can get $18 off rental of any cameta body, valid for collections on 20-22 Sep 2012. Do check it out!
Oh yes, aside to this, do remember that Tripod is not allowed but monopod will be allow. Happy shooting to all fellow photography lovers who are attending F1 for these 3 days!
Disclaimer: This is not a sponsored post nor advertorial post. Above recommendation purely based on personal experience.