WHAT TO WATCH

FOR SUHR:

The women’s pole vault starts with a qualification round. Katerina Stefanidi of Greece will be the favorite after winning Olympic gold in Brazil last August. She will be tested by American Jenn Suhr, who won the event at the 2012 London Olympics.

Sidelined by an injury, Greg Rutherford of Britain won’t defend his world long jump title as qualifications begin. Jeff Henderson of the United States is the reigning Olympic champion, while Olympic silver medalist Luvo Manyonga of South Africa has the top mark this season.

LONG & SHORT OF IT: CASTER & COMPANY:

Olympic 800-meter champion Caster Semenya will compete in the opening round of the 1,500 meters. The South African runner has long been embroiled in the controversial debate in track and field over women with very high levels of testosterone being allowed to compete. American Jenny Simpson, the 2016 Olympic bronze medalist, sidestepped the issue. “According to the rules, she’s allowed to toe the line and so I’m going to try to beat her,” Simpson said.

HULK GOES FOR REPEAT:

Robert Harting sure made an impression on his trip down the track at the London Olympics. He tore off his shirt and flexed his muscles, Incredible Hulk style, and ran down Lane 9, clearing every hurdle along the way. Not bad for a discus thrower. The German returns to the site of his showy Olympic triumph. Prelims are Friday, and Harting is seeking his fourth world title. His main competition is expected to come from Piotr Malachowski of Poland. Malachowski and Harting have combined to win the last four world titles.