Brisbane - Bulgaria's Grigor Dimitrov launched his campaign to return to the world's top 10 when he outlasted fifth-seeded Frenchman Gilles Simon in the opening round of the Brisbane International on Monday.
The powerful Bulgarian saw off Simon 6-3, 7-6 (12/10) in two hours and five minutes to move into the second round of the season-opening tournament.
Dimitrov had a disappointing 2015, slipping from 11th in the world to his current ranking of 28, but during Monday's match he showed glimpses of the form that saw him touted as a future top-five player.
He broke Simon once in the first set then recovered from losing his serve early in the second set to take it to a tiebreak.
The big-serving Dimitrov always looked the more dangerous in the tiebreak and skipped out to a 6-4 lead.
However, Simon battled back and saved three match points against an increasingly nervous Dimitrov.
The Bulgarian had three more match points but finally sealed the win on his seventh when he blasted a serve at the Frenchman's body, which Simon bunted wide.
Dimitrov will now play either American Steve Johnson or Serbia's Victor Troicki in the second round and is on track for a quarter-final clash against top seed Roger Federer, a repeat of last year's semi-final which the Swiss ace won 6-2, 6-2. Federer has received a bye into the second round.
American Denis Kudla moved into the second round when he downed Australian wildcard John-Patrick Smith 4-6, 6-3, 6-2.