The Luxembourgish athlete took part in the Czech Indoor Gala in Ostrava on Wednesday.

Grethen was the last person to set a new Luxembourgish record for the 1,500m distance, which he now managed to break again. The CSL athlete beat his recent time by 3 seconds and 15 hundredths. The national record now stands at 3 minutes, 39 seconds, and 49 hundredths.

Grethen's performance in Ostrava was rewarded with a silver medal.