W2W4: Allyson Felix, Simone Biles top Monday's must-watch list

— -- RIO DE JANEIRO -- Here is a look at some of the top events to keep on your radar Monday:

Women's 400-meter final (10:45 p.m. ET): Allyson Felix looks to win her fifth career Olympic gold medal in the 400 final after posting the best time (49.67) of the semifinal heats. The American was originally vying for the 200-400 double in Rio (after competing in the 100 and 200 four years ago in London), but she failed to qualify in the 200 in part because she lost training time due to an ankle injury from earlier in the year. Also keep an eye on Oregon football player Devon Allen, who makes his Olympic debut in the men's 110 hurdle heats.

• Complete track and field coverage

Women's, men's individual events; coverage begins at 1 p.m ET: Simone Biles has already made history by becoming the first American female gymnast to win three golds in one Olympics. She'll look for her fourth when she competes in the balance beam final. Her main challenger might be teammate Laurie Hernandez, who beat Biles in the beam at trials in July.

• Complete gymnastics coverage

Men's omnium, 4:23 p.m. ET: Mark Cavendish goes from sprint finishes on the road to the oval of the Velodrome, as he looks to win his first Olympic gold medal. The winner of 30 Tour de France stages, Cavendish looks to catch defending Olympic champ Lasse Norman Hansen of Denmark.

• Complete cycling coverage

Women's open-water 10km: After months of reports and tests and doubts about the water quality in Rio, racers will swim along Copacabana Beach for 6.2 miles. What debris does or doesn't show up along the course will potentially depend on wind conditions and currents.

• Complete swimming coverage

Quarterfinals, U.S. Women versus Brazil, 1:10 p.m. ET: After going 3-0 in group play, the defending champion U.S. team must get past host Brazil in their first match of the knockout round. The other matchups: Italy-China, Australia-Hungary and Russia-Spain.

• Complete water polo coverage