Ashleigh Barty claimed the biggest victory of her singles career, defeating Karolina Pliskova in straight sets to win the Miami Open title.

The 12th seed, whose recent success ensures she is moving into the top 10 of the world rankings, added to her previous three WTA Tour singles titles and her 2018 US Open doubles success with a 7-6 (7-1) 6-3 victory.

Barty had knocked out Kiki Bertens, Petra Kvitova and Anett Kontaveit in her run to the final, and she stepped up when it mattered in the breaker to clinch the first set against Pliskova.

The Australian's strong serve then saw her home, dropping just two points on her serve in the second set and breaking Pliskova twice to claim the win.

The pressure of a first WTA Premier Mandatory-level final may have got to Barty early on as she was broken in just her second service game, only to recover and hit back on the Pliskova serve to level at 3-3.

Neither player could create another first-set break-point opportunity and it was one-way traffic in the breaker, Pliskova losing her way with three successive unforced errors, leaving Barty one set from victory.

The trophy came into closer view when Barty came out on top in a mammoth first game of the second set, finally breaking at the fifth time of asking when Pliskova pushed a forehand long.

Pliskova was afforded barely any chances to hit back on the Barty serve, the Australian finishing the match by winning 86 per cent of her first-serve points and delivering 15 aces.

Three winners gave Barty a trio of championship points on the Pliskova serve and the Czech went long with a forehand again to settle the contest in her opponent's favour.