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Sierra, a talented young competitor, achieved a career-high ranking of No. 64 after a productive clay-court season.
The women's side remains highly open. Fourth seed Coco Gauff launches her title defense against Taylor Townsend.
World No. 1 Aryna Sabalenka has had a poor clay-court season but remains a top contender.
The top half also features fifth seed Jessica Pegula and ninth seed Victoria Mboko.
The bottom half is equally stacked.
Recent Italian Open champion and seventh seed Elina Svitolina could face third seed Iga Swiatek, who hopes her new coaching partnership with Francisco Roig can propel her to a fifth French Open crown.
Swiatek is on course to meet 2017 champion Jelena Ostapenko in the third round, an opponent who holds a 6-0 head-to-head record against her.
Second seed Elena Rybakina is chasing her second consecutive grand slam after winning Melbourne.
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Based on seedings, she is projected to face eighth seed Mirra Andreeva in the quarterfinals.
