British number one Johanna Konta reached the last 16 of the Miami Open after seeing off Russian Elena Vesnina in a third-set tie-break.
Konta dropped the first set but came back to win the second emphatically before pulling through in a tight decider, winning 4-6 6-1 7-6 (7/3) in two hours and 24 minutes.
A single break in the seventh game was enough for Vesnina to win the opener and when Konta sent a service return long to end the set, her body language betrayed her frustration.
But she was a different player in the second set as she broke in the second game and saved a break point in the next. She pulled away from there to win 6-1, rounding the set off in fittingly comprehensive fashion with an ace.
She broke to lead 4-3 in the decider but was pegged back straight away and found herself serving to stay in the match at 5-6. It proved a nervy game as she started with a double fault and trailed 15-30, but she battled back and won a fantastic exchange of volleys at the net to force a tie-break.
She quickly went down a mini-break at 1-2 after missing a backhand volley, but drew level straight away and from 3-3 at the change of ends, she pulled away to win and set up a clash with Romania's Monica Niculescu, a straight-sets winner over CoCo Vandeweghe.