Taylor Fritz's girlfriend, Morgan Riddle, has joined French Open champion Coco Gauff to congratulate the American on his Stuttgart Open victory.

German 17-year-old Justin Engel reached a quarter-final of an ATP Tour event for the first time in his young career. He achieved that on Thursday at the Stuttgart Open with a 6-4, 6-4 win against seventh seed Alex Michelsen in the last 16.

Taylor Fritz, who beat Alexander Zverev in the final at Stuttgart at the weekend to make a strong start to the grass court season, reclaimed his place in the top four in the ATP rankings on Monday.

STUTTGART, GERMANY (AP) _ Results Sunday from Boss Open at Tennis Club Weissenhof (seedings in parentheses): Santiago Gonzalez, Mexico, and Austin Krajicek, United States, def. Rajeev Ram and Alex Michelsen, United States, 6-4, 6-4.