Dietzel put together rounds of 71-68-72-69, and even though Van Tilburg, a Dutchman, clipped him by one in the final round, Dietzel had already put the work in early week.
For Dietzel, the last major golf highlight came in 2018 when he won the German Junior. He has played three PGA Tour Germany events in 2019, but has missed the cut in each one.
Behind Van Tilburg, the next-closest player was England’s James Cass at 3 over. Cass started the week with the lead after an opening 69, but never could regain the top position after a second-round 73.
Roussin-Bouchard won the Portuguese Amateur title in February.
Italy’s Alessia Nobilio was second at even par, followed by Switzerland’s Elena Moosman. Other notable names include GB&I Curtis Cupper Lily May Humphreys, who was in fifth, and Austrian Emma Spitz, winner of the Girls British Open Amateur, in sixth.
Spitz, Nobilio, Humphreys and Caterina Don, who was in eighth, will all play the Augusta National Women’s Amateur next month. So will Annabel Fuller, who finished in the top 30 in Italy.



