Former US Open champion Sloane Stephens has been bundled out of the Brisbane International in the first round by Briton Johanna Konta.

A 2016 Australian Open semi-finalist, world No.37 Konta upset third-seeded American Stephens 6-4 6-3 in under two hours to book a second round clash with Australia’s Ajla Tomljanovic.

World No.46 Tomljanovic began her Brisbane campaign with a 1-6 6-3 6-0 win over Czech Katerina Siniakova.

Contesting the Brisbane event for the first time in five years, world No.6 Stephens began sluggishly against Konta in their first career meeting and was punished for a string of unforced errors.

The 2017 US Open winner Stephens’ only respite came at 1-0 down in the second set when play was suspended for several minutes when a member of the crowd was treated for a medical issue.

Stephens, 25, had hoped to pick up where she left off in 2018 after entering a new season ranked in the world’s top 10 for the first time.

However, Stephens must now reload at next week’s Sydney International in her final hit-out before the opening grand slam in Melbourne.

It marked the 27-year-old Konta’s 15th career victory over a top 10 opponent and first since knocking over world No.2 Simona Halep at 2017 Wimbledon.