El Aynaoui has been enjoying the best form of his career as he approaches 30 but has had something of a slump in recent months.
World ranking: 22
US Open best:
2001: 1st round
2000: 1st round
Since reaching the final on home soil in Casablanca in May, losing to Julien Boutter, he has managed just one quarter-final in Germany.
It would be understandable if he was still tired from an epic quarter-final at the Australian Open in January, going down 21-19 to Andy Roddick.
El Aynaoui had his best win of the year in the previous round, beating top seed Lleyton Hewitt, and his form over the last two years has generally been good.
Last season was the most successful of his lengthy career, reaching five finals, winning events in Doha, Casablanca and Munich.
El Aynaoui has one of the best forehands in the game and, if he can rediscover his best form, could well match last year's run to the quarter-final.