Nick Kyrgios overcame early back spasms to get the better of Russia's Daniil Medvedev in a pair of tiebreakers and win the Citi Open in Washington on Sunday. The Australian won 7-6(6) 7-6(4) over frustrated fourth-seed Medvedev for his sixth career ATP Tour victory. Kyrgios did not face a single break point and hit 18 aces, including two to close out the final. Kyrgios, mixing baseline rallies with drop shots, came from 4-1 down in the opening tiebreak to win it and took a medical time-out after the set, which seemed to help relieve the back spasms that had him stretching on the court during changeovers. However, he still had trouble with Medvedev's serve, the Russian winning 80% of his service points for the match. Kyrgios tied the second set at 6-6 before claiming his second victory of the year, again prevailing in a tiebreak.