The British No. 1 was the eighth seed in the qualifying competition, but had to battle hard to make it through her opening match with Mirjana Lucic-Baroni of Croatia.
Having taken the opening set 6-3, Watson was then pegged back as Lucic-Baroni won the second on a tiebreak that went to 9-7.
The Sarnian responded well, though, and claimed the deciding set 6-4 to progress after 2hr 4min.
Yesterday's qualifying final proved to be far more straightforward for Watson.
She was up against Tamira Paszek, who had knocked out 16th seed Donna Vekic in the first qualifying round, but the Austrian lasted exactly half the time Lucic-Baroni had done the previous day as Watson won in straight sets 6-3, 6-2.
The first-round draw has been relatively kind to the Sarnian and she will face fellow qualifier Tereza Smitkova this afternoon.
Before the WTA rankings had been updated this morning, the Czech Republic player was 41 places below Watson in the world list.
However, Smitkova came through both her qualifying matches in straight sets including a 6-4, 6-1 win over Elena Vesnina yesterday.
The winner of today's match, which is due on court at around 7pm BST, will face either 10th seed Dominka Cibulkova or wild-card Francoise Abanda in the second round.