Answer
Grigor Dimitrov has reached the finals of a doubles tournament twice. The first time was in 2014 at the Mutua Madrid Open, where he partnered with Rafael Nadal. They lost in the final to Juan Martín del Potro and Stanislas Wawrinka. The second time was in 2017 at the Shanghai Masters, where he partnered with Jack Sock. They lost in the final to Pierre-Hugues Herbert and Nicolas Mahut.