The 21 - year - old Serbian has vaulted 300 ranking spots in the last two years .
The 21 - year - old Serbian reached a career high of No. 102 on May 12 , 2014 .
The 21 - year - old Serbian has vaulted 300 ranking spots in the last two years , and reached a career high of No. 102 on May 12 , 2014 .