LONDON (CNN) -

It's a big day at track and field, topped by the always exciting men's 1,500-meter final. In other notable events, several athletes say farewell to the London Games while others look for one more shot at glory.

Here are five things to look for Tuesday at the 2012 London Games:

1. Women's gymnastics floor: Wieber's last chance

Jordyn Wieber of the United States didn't have a chance for an all-around gold, but Tuesday she could medal in her last event of these Games. She takes part in the floor competition, where she scored a 15.000 during the team competition. Her teammate Aly Raisman also has podium hopes and comes into the event having scored the best marks in the event at the London Olympics.

Event begins at 4:23 p.m. London time (11:23 a.m. ET)

2. Men's 1,500 meters: Could be a Kenyan sweep

Kenyan Asbel Kiprop, who won the 1,000 meters in Beijing at age 19, has run the best time in the world this year, but will be tested by countrymen Silas Kiplagat and Nixon Chebseba. Also keep an eye on Algeria's Taoufik Makhloufi, who was reinstated after the governing body of track and field originally had expelled him from the Games for failing to race hard in his 800-meter heat. A doctor's note convinced the IAAF that Makhloufi has a knee injury.

Event begins at 9:15 p.m. London time (4:15 p.m. ET)

3. Men's soccer: Final four time

One Japanese team is already in a football final, now the men hope to equal the women's side, with a win over Mexico in the Olympic semifinals. Giovani dos Santos is the top offensive threat for Mexico, which entered the tournament as one of the medal favorites. Brazil faces South Korea in the other match. Brazil has scored three goals in each of its four wins, and is led by Neymar, one of the most exciting young players in the world.

Mexico plays Japan at 5 p.m. London time (noon ET) while the South Korea-Brazil match starts at 7:45 p.m. London time (2:45 p.m. ET)

4. Beach volleyball: Can top-ranked team spring an upset?

Misty May-Treanor and Kerri Walsh Jennings made news at this tournament when they lost a set. Not a match, a set. The two-time defending champs face Zhang Xi and Xue Chen of China, the top-ranked team in the world, in one contest. Despite the Chinese pair's ranking, most experts are picking the U.S. greats to win. In the other match, Brazil's Juliana and Larissa, second in the world ratings, will play Americans April Ross and Jennifer Kessy.

Women's semifinals begin at 6 p.m. London time (1 p.m. ET)

5. Men's Cycling: Keirin on

Chris Hoy of Great Britain wants to wrap up his Olympic track cycling career by defending his title in the keirin and breaking a British mark for golds. Hoy is tied with rower Steve Redgrave for a Team GB record five gold medals. Keirin events feature six racers being paced for 5 ½ laps then sprinting for 2 ½ laps on the velodrome track. Crashes in final curve are not uncommon as the pack heads for the finish line.

The final is scheduled for 5:57 p.m. London time (12:57 p.m. ET)