This came through as she gathered herself superbly for the battle to come back, withstanding Vekic's rampant shotmaking to focus on executing the basics on key points. A first ace staved off a point for Vekic to go up a double break, with a neat forehand angle sealing that hold - and when the US Open quarterfinalist carelessly lost control of her forehand in the next game for Bertens to get back on serve, the 27-year-old needed little further encouragement to turn the match into a battle of wills - and serves.
Bertens' renowned delivery was crucial to her comeback. Under pressure again in the seventh game, she would save three break points - two with simple one-two punches - and close out the hold with three consecutive service winners to move ahead for the first time.
Although both players were now sufficiently grooved on serve to post five straight holds without another break point hoving into view, it was again Bertens who out-competed Vekic on the biggest points to squeeze through the tiebreak. Down 4-5, the 2016 Roland Garros semifinalist came up with a brace of brilliant backhands down the line - the second a pass off a rather tentative Vekic approach - before an errant Vekic forehand sealed the set.
@kikibertens on the move@WTAEliteTrophypic.twitter.com/e2xI9DamOO"The first set was really tight, so it was just a few points here and there," recalled Bertens afterwards. "I just was trying to push myself all the time. It was tough, I would say, mentally but also physically. We were both struggling, I think, a little bit. But from 5-4 down I played two really good points."