American sprinter Tyson Gay has claimed that an Olympic medal is the "missing piece" in his life.

The 29-year-old failed to reach the 100m final in Beijing four years ago due to fitness problems and he admits that he is feeling the pressure of competing against current champion Usain Bolt.

Gay said: "To come here and compete for a medal really means a lot after I came up short in 2008. There is a lot of pressure for me, I am not going to lie.

"There would still be pressure if I did get a medal in 2008, but it's a lot more now because I really feel the missing piece of my heart is an Olympic medal.

"I have a lot of driving force coming into these Games. I am fully focused on leaving with a medal."

Despite struggling with injuries throughout his career, Gay is the only sprinter other than Bolt to record a time below 9.7s.