One of Wall Street's top commodity strategists sees the latest OPEC meeting taking on renewed importance.

RBC Capital Markets' Helima Croft, who'll be attending Thursday's gathering in Vienna, told CNBC there's an emerging Russia factor — and it's contributing to jitters in the oil market.

According to Croft, there's a chance Russia won't agree to rollover the 1.8 million barrel a day production cut for all of 2018, a plan that has been expected to get approval. She noted a number of major Russian oil firms have been expressing their displeasure about extending the agreement.

"If Russia is not willing to sign up again to extend the cut, people fear that we're going to get something shorter than anticipated," the firm's Global Head of Commodity Strategy said recently on CNBC's "Trading Nation."

Croft's latest take on the global oil markets comes as crude oil hit $58 a barrel last week for the first time since 2015. WTI Crude oil is now up 8 percent for the year, but down more than 40 percent over the past ten years.

"From a price perspective, some of the risks are really to the downside because if we don't get a full extension for all of 2018, I think this market could sell off very similar to what happened in May when the statement out of OPEC did not reach market consensus and expectations," she said.

At that time, crude oil prices fell 2 percent. Since then, prices have rebounded by 20 percent.

Even though Croft believes there's more downside risk in the oil markets right now, there is one thing in particular that could lift prices.

Croft, a CNBC contributor, is also watching OPEC member Venezuela. Its state oil company has been on the brink of default.

"The big wildcard for Q1 [2018], I think, is going to be what happens to a country like Venezuela," Croft said. "Do we really start to see those barrels roll off the market in a lot faster fashion? That could be one of our big upside stories."