EUGENE, Ore. — The headlines say youth is being served on the U.S. Olympic track and field team.

The numbers say that’s nothing new.

With the second half of Olympic track trials set to start Thursday, 35 of the 50 athletes who have guaranteed themselves trips to Rio de Janeiro will be going to their first Olympics.

The U.S. team includes 18-year-old high jumper Vashti Cunningham, the world indoor champion, who will be the youngest U.S. track and field athlete to qualify for the Olympics since Carol Lewis in 1980, and high jumper Chaunte Lowe and sprinter Allyson Felix, both of whom are in their 30s and going for the fourth time.

“You look at the system we have and the depth of talent we have, and one thing that’s fairly consistent is we’ll have an amazing team and amazing athletes,” said Max Siegel, the head of the U.S. track federation. “It’s just a matter of who the stars are going to be.”

The U.S. won 29 medals at the London Olympics four years ago. That number dwindled to 18 at last year’s world championships, raising alarm.

Over the years, the top three finishers in each event at the trials make it, assuming they meet an Olympic qualifying standard. There are no exceptions for injuries or past performances as there is elsewhere, including Jamaica, where Usain Bolt will almost certainly be on the team despite pulling out of Jamaica’s qualifier with a hamstring injury.

It may be the fairest system, but, as decathlete Ashton Eaton said, “if the goal is to send the best team, I’m not sure the trials method is the best method.”

For instance, a tangle of feet in the stretch of the women’s 800-meter final knocked out Brenda Martinez and Alysia Montano, either of whom would have contended for medals. Making it instead were three first-timers: Kate Grace, Ajee Wilson and Chrishuna Williams.

“Surreal,” said Grace. “I’ve never podiumed at a national event and now I’m going to the Olympics. I knew I could run at this level even though I’d never done it before.”

MEN’S BASKETBALL: Canada, Serbia and Greece clinched semifinal berths in the tournaments that determine the final spots in the field.

Cory Joseph of the Toronto Raptors scored 13 points as the Canadians beat Senegal 58-55 to improve to 2-0 in Group A of the Manila, Philippines, tournament. Canada will face the loser of the France-New Zealand game, which will be played Thursday, in the semifinals.

Serbia also improved to 2-0 in the tournament it is hosting in Belgrade by beating Angola, 83-60. Nikola Jokic of the Denver Nuggets finished with 17 points and six rebounds.

Greece beat Mexico 86-70 in a game that determined first place in Group A in Turin, Italy. Mexico will play Italy in one semifinal and the Greeks will face Croatia.

The three tournament winners get the final berths in Rio.

ARIES MERRITT, the defending Olympic champion, rushed back from a kidney transplant to be ready for Rio. He won’t let Zika stand in his way, no matter how much his doctors object.

Qualifying in the 110-meter hurdles at the U.S. trials begins Friday. Should Merritt make the team, he said he won’t think twice about racing in Rio even though the mosquito-borne virus could pose a greater risk due to the transplant.

“(The doctors are) very, very concerned. They’ve asked me many times: ‘Have you considered not going?’ ” said Merritt, who holds the world record (12.80 seconds in September 2012). “I’m like, ‘That’s not an option. If I make it I’m going.’ ”

The reason is simple: At 30, he doesn’t know if this chance will come around again.