Kyle Edmund saw off Davis Cup teammate Dan Evans in straight sets in the first round of the Monte Carlo Masters.
Edmund, ranked one place below Evans at 45 in the world, recovered from a slow start to win 7-5 6-1, BBC reported.
The 22-year-old from Yorkshire, who rates clay as his favorite surface, will play nine-time Monte Carlo champion Rafael Nadal in round two.
Andy Murray, who watched compatriots Edmund and Evans from courtside, plays his opening match tomorrow.
The world number one will take on Luxembourg's Gilles Muller or Tommy Robredo of Spain.
Edmund and Evans were Davis Cup teammates in Britain's quarterfinal defeat by France earlier this month, but were pitted against each other for the first time on the ATP Tour in Monte Carlo.
The surface made the big-hitting Edmund a heavy favorite against Evans, who has just two main draw wins to his name on the surface.
However, Edmund opened with two double faults and looked nervous, slipping 4-1 down as Evans capitalized on the errors.
The 26-year-old from Birmingham could not maintain his advantage though, with Edmund fighting back to claim the set with the seventh break of serve in 12 games.
Edmund had to save break points again at the start of the second but, despite some wayward smashes, went on to dominate, sealing it with an ace after one hour and 20 minutes.
Andy Murray, who watched compatriots Edmund and Evans from courtside, plays his opening match tomorrow.
The world number one will take on Luxembourg's Gilles Muller or Tommy Robredo of Spain.
Novak Djokovic will also return to the tour at the Monte Carlo Masters this week after recovering from elbow injuries.
Djokovic, ranked second, said he "feels great" after coming back with a win in the Davis Cup last week.
Like Murray, the Serb missed last month's Miami Masters will play his first clay-court match of the year when he takes on Frenchman Gilles Simon.