Second seed Tomljanovic was a 7-5 6-2 victor against Anna Karolina Schmiedlova, reeling off the last four games in succession to advance in Morocco.
Fellow Australian Astra Sharma joined her in the last eight by overcoming wildcard Petra Marcinko 5-7 6-3 6-3.
Kristina Mladenovic had to save a match point after passing up two herself to finally get over the line with a 6-3 3-6 7-6 (9-7) success - her first singles win of the year - over lucky loser Tessah Andrianjafitrimo in a first-round clash.
At the Internationaux de Strasbourg, third seed Cirstea stormed to a one-set advantage against Ekaterina Makarova but soon fell away and succumbed to a 1-6 6-3 6-2 loss.
Magda Linette breezed past Heather Watson 6-1 6-1 to reach the quarter-finals, where she was joined by Maryna Zanevska after the Belgian's 4-6 7-5 6-1 comeback win against Harmony Tan.
Top seed Karolina Pliskova awaits American Bernarda Pera who defeated Elena-Gabriela Ruse in straight sets, while Anna-Lena Friedsam will take on Elise Mertens after rallying to beat Daria Saville 4-6 6-3 7-6 (7-5).