TORONTO -- Modern pentathlon at the 2015 Pan American Games presented one of the first opportunities for a member of Team USA to qualify by name for the Rio 2016 Olympic Games, but in the high-pressure, high-temperature environment in Toronto, two Team USA athletes weren’t able to pull it off.

With an eighth-place finish, defending Pan American Games champion Margaux Isaksen has now missed three opportunities to punch her ticket to Rio. Teammate Samantha Achterberg’s 10th-place finish also was not enough.

“It was definitely a hot day today so it was difficult, but definitely no excuses,” Achterberg said of the conditions during the combined running and shooting portion of the event. “All the competitors were in the same position.”

Both U.S. athletes were off to slow starts, holding 13th and 20th-place rankings after the first event, fencing. While Isaksen seemingly made up ground in the 200-meter freestyle swim after posting the second-best time, her show jumping ride atop Tango was not good enough to propel her to a top position leading into the combined event. Isaksen’s handicap time of 1:42 and Achterberg’s 2:02 were long enough to put the podium just out of reach.

Achterberg, who entered the day ranked 35th in the world, has been training with Isaksen for the past five years at the U.S. Olympic Training Center in Colorado Springs, Colorado. Pan Ams marks her first major multi-sport international tournament.

“World championships is huge competition-wise, but I think this is a whole different level of being only two athletes and being kind of like a mini Olympics,” Achterberg said.

Unlike her teammate, Isaksen has plenty of experience on the world stage. She entered the Games as the ninth-ranked pentathlete in the world after landing a spot on the podium in all three UIPM world cup competitions she entered this season, claiming three silver medals. At an inopportune time with Rio qualifications on the line, her momentum faded and she failed to medal in individual competition at both the world cup final and world championships.

The Pan Am Games seemed to be a perfect opportunity to get back on track as Isaksen was billed the second-highest ranked athlete hailing from the Pan American region behind Brazil’s Yane Marques (ranked sixth). Marques, a familiar face in international modern pentathlon competition, finished just one spot ahead of Isaksen to take home the bronze medal at the London 2012 Olympic Games. She would ultimately claim the 2015 Pan Am gold while Mexico’s Tamara Vega and Mayan Oliver took silver and bronze, qualifying all three to the Rio Games.

The next opportunity for U.S. modern pentathletes to qualify for Rio won’t come until the UIPM season reconvenes in the late winter and early spring months.