Google Cloud Chief Executive Officer Diane Greene, who has pushed for three years to catch up with market leaders Inc. and Microsoft Corp., will step down from her post and be succeeded by former Oracle Corp. executive Thomas Kurian.

Greene, 63, will remain CEO through January, working with Kurian, who will join the Alphabet Inc. (GOOGL.O) unit Nov. 26. Greene said in a blog post that she will stay as an Alphabet board member.

During her tenure in charge of the one of the internet giant’s central units, Greene rapidly expanded the business, hiring a major new salesforce and investing hundreds of millions of dollars in servers and undersea cables. Still, Google cloud is seen by analysts as a distant third in the U.S. to Amazon and Microsoft in the market for running apps and storing data in the cloud, despite having a head-start on Microsoft that predated Greene’s time at the company.

Greene is also one of Google’s most prominent female executives. Her departure highlights the gender imbalance in the management ranks of a company that is grappling with criticism over how it has treated its female employees, especially in regards to sexual harassment.

Greene said she plans to turn her attention to mentoring and education. Before joining Google, Greene was a founding member and eventual CEO of software company VMware, which EMC Corp. bought in 2004 and is now part of Dell Technologies Inc.

In her post, Greene praised her staff for boosting Google’s business. “The cloud space is early and there is an enormous opportunity ahead,” she said.

With Kurian, Google will be getting an executive who used to supervise cloud development at Oracle, the world’s second-largest software maker. Kurian had a difficult time transitioning the company to cloud computing. After years of effort, Oracle struggled to gain much traction against Amazon Web Services and Microsoft’s Azure. He’ll now have a chance to try it again.

Kurian spent 22 years at Oracle, where he grew into a powerful acolyte of Executive Chairman Larry Ellison. He departed the company in September as president of product development, the company’s fourth-highest role. Kurian was said to have disagreed with Ellison on the direction of Oracle’s cloud business, Bloomberg reported in September, leading to Kurian’s leave of absence and eventual resignation.

Kurian climbed through the ranks of the software maker by spearheading products that accelerated sales growth, such as middleware, but got his start as a consultant at McKinsey & Co.