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With Atlanta top of the Eastern Conference, the club were keen to retain the former Barcelona and Argentina coach for 2019 and beyond.

But Martino, who has been linked with becoming Mexico coach, could not reach an agreement with the club over a new deal.

"This was not an easy decision to make," Martino told the club's website. "I have enjoyed my time with Atlanta United very much and am proud of what we have accomplished together in such a short time.

"The decision was not made for financial reasons, negotiations with the front office were transparent and fair. It was simply the right move for me and my family at this time. 

"The opportunity to build a team from the start does not come along often, and I am grateful to the club and to the fans for putting their trust in me to establish a solid foundation here in Atlanta. What is most important now is that the focus remain on our goals for this season."

No MLS team have claimed more points or scored more goals since Martino took charge than Atlanta and president Darren Eales thanked the coach for his efforts.

"We are very grateful to Tata for his commitment to Atlanta United and for all he has done to help build our club during our first two years in the league," Eales said.

"True to his reputation, he has been an incredible leader and has set us up for great success moving forward. From the beginning, his vision for Atlanta United was aligned with ours, and his level of experience, talent and leadership has been extremely valuable during this critical time. 

"He will be missed, but we understand and appreciate his reasons for moving on to spend time with family and take on new challenges."