Delbonis earned five Challenger and Futures titles from the time he turned professional in 2009 until 2013.
He qualified at the 2013 International German Open and beat Tommy Robredo, Dmitry Tursunov and Fernando Verdasco. He beat the Spaniard in a tight three-setter to set up a meeting in the semifinals with Roger Federer. Here, Delbonis scored by far the biggest win of his career, defeating Federer (who was hobbled by a back injury that he suffered in the previous round) in two tiebreaks to book his place in his first ATP Tour final. He finished runner-up to Fabio Fognini, squandering a set and 4–1 lead and failing to convert three match points. This performance raised his ranking into the top 100 for the first time in his career.
He went on to win his first ATP title the next year when he defeated Paolo Lorenzi, 4–6, 6–3, 6–4, at the 2014 Brasil Open. It was their first tour level match against each other, however Lorenzi has won against Delbonis in past three Challenger events. The win enabled to reach a new men's singles high ranking of 44.
Won tournament; or reached Final; Semifinal; Quarter-final; Round 4, 3, 2, 1; competed at a Round Robin stage; lost in Qualification Round; absent from tournament event; played in a Davis Cup Zonal Group (with its number indication) or Play-off; won a bronze, silver (F or S) or gold medal at the Olympics; a downgraded Masters Series/1000 tournament (Not a Masters Series); or a tournament that was Not Held in a given year.
To avoid confusion and double counting, these charts are updated either at the conclusion of a tournament, or when the player's participation in the tournament has ended.