Raonic, who has not played in Washington since he won the title three years ago, will be looking for his first ATP title of the year after a mixed season to date, whilst Dimitrov will be making his fifth appearance at the tournament as he looks for a third singles title of the year.
The Canadian and the Bulgarian, both top-ten players, join an extremely strong field at the Citi Open, which includes the likes of defending champion Gael Monfils, Kei Nishikori, and Dominic Thiem.
Raonic and Dimitrov look for hard court success
The decision to hand both Raonic and Dimitrov, two of the most notable names on the ATP Tour, wildcards into the tournament which takes place in less than two weeks time is undoubtedly an interesting one, with both men in with a chance of featuring towards the business end of the tournament.
It has been a fairly solid season so far for Dimitrov, who is back in the top ten of the rankings after starting the season ranked 17th. The Bulgarian has won two titles this season, in Brisbane and at his home tournament in Sofia, as well as reach the last four in Melbourne, and after regaining some form over the grass court season he could be dangerous in Washington.
Meanwhile, it has been a fairly mixed season for Raonic, who has struggled with injury and inconsistency in 2017. The Canadian is yet to win a title this year, withdrawing from the Delray Beach final and losing to Marin Cilic in Istanbul, and failed to defend his Wimbledon finalist points last week. Raonic will be hoping to channel his run of 2014 in Washington, where he beat the likes of Lleyton Hewitt and Steve Johnson before beating Vasek Pospisil in the first all-Canadian final in ATP history.