The world number two, who won the Dubai Duty Free Tennis Championships in February before the WTA Tour's suspension for the coronavirus pandemic, sealed a 6-2 7-5 victory on Monday (AEST). 

A very different story looked set to unfold after Mertens won the first two games, but Halep clicked into top gear to reel off six on the bounce and take the set. 

When Halep continued her streak by breaking in the first game of the second set, the writing appeared to be on the wall for Mertens. 

But the Belgian, chasing a sixth singles title, hit back immediately to keep her hopes alive. 

Ultimately, however, the class of two-time grand slam winner Halep told and the Romanian will soon have to confirm whether she will seek to cash in on this form by competing at the US Open, which has suffered from a spate of withdrawals over COVID-19 fears.