Stuttgart's ATP claycourt tournament will become a grasscourt event from 2015 with organisers promoting it as a key Wimbledon warm-up.
The tournament's request to move to grass and take place the week following the French Open was approved by the ATP Board of Directors at its recent meeting in Miami.
With Wimbledon taking place a week later in the calendar from 2015, a three-week gap will be incorporated in the calendar in between Roland Garros and the season's third Grand Slam event, meaning an additional week of tournaments.
"The ATP is pleased to confirm that the request by the MercedesCup in Stuttgart to move to a grass court event in the week after Roland Garros from 2015 has been approved by the ATP Board of Directors," said ATP president Brad Drewett.
"The MercedesCup in Stuttgart presented an extremely thorough application and we have full confidence that they will deliver a high-level ATP grass court event in the lead up to Wimbledon.
"As part of our process in setting the 2015 ATP World Tour calendar, we continue to review other options for the three-week period between Roland Garros and Wimbledon in 2015."
The new-look Stuttgart event will join Queen's Club, Halle, Eastbourne, ‘s-Hertogenbosch and Newport as ATP World Tour grass court tournaments.
At the moment, the Stuttgart tournament is played on clay, the week after Wimbledon.