Holger Rune made his debut in the Top 5 of the Pepperstone ATP Rankings on Monday, but was unable to finish his first match as a member of that elite club.

Trailing 4-6, 0-2 against Mackenzie McDonald on Wednesday at the Western & Southern Open, the 20-year old was forced to retire. Following the first set, he received treatment on his lower back area from an ATP physiotherapist at the Cincinnati ATP Masters 1000. He lost five straight games from 4-3 in the first set before bowing out.

Rune was seeking his first win since he reached the Wimbledon quarter-finals, following an opening-round defeat to Marcos Giron last week in Toronto.

With the retirement, McDonald picked up his fourth Top 10 win of 2023 (4-2) and the fifth of his career. He defeated sixth seed Andrey Rublev last week in Toronto en route to his first ATP Masters 1000 quarter-final.