Keys sailed through the first set in 31 minutes, but she wound up in the tie-break after both players dropped their final serves. The American had three match points and couldn't convert, then fended off four set points before capturing the title on the fifth try of the one-hour, 13-minute set.

For Keys, the victory was the seventh singles title of her career. She won her maiden title at Eastbourne in 2014.

Keys moved to 9-2 head-to-head against Kasatkina. This was their first matchup on grass.

Bad Homburg Open

Katerina Siniakova (27) of the Czech Republic captured her first grass-court title with a 6-2, 7-6 (5) victory against Lucia Bronzetti (24) of Italy in Bad Homburg, Germany.

Bronzetti trailed 5-2 in the second set before winning 13 consecutive points and ultimately forcing the tiebreak.

Siniakova overcame seven double faults and finished the match in one hour, 36 minutes.

It was the fourth career singles title and first of the season for Siniakova, a seven-time Grand Slam doubles champion who was competing in just her third event since injuring her right wrist at the Miami Open in March.