What Olympic marathon runner collapsed near finish line whilst in the lead?

Answer 1

Los Angeles 1984

Roughly 24 minutes after winner Joan Benoit (USA), had entered the final lap the Swiss runner Gaby Andersen-Scheiss staggered into the tunnel leading to the main stadium's track. Cap in hand and drenched in perspiration she began a painfully cruel yet truly Olympic final 400 metres, cheered by the crowds as she lurched towards the finish line

Answer 2

Dorando Pietri of Italy at the 1908 Games in London.

Pietri was at the brink of exhaustion as he entered White City Stadium at the end of the marathon and fell several times on his way to the finish line. Each time he fell he was helped up by officials. Although he crossed the finish line in first place, he was disqualified for receiving help from the officials.

Queen Alexandra presented Pietri with a silver cup for his effort and courage following the disqualification.