Apple’s fiscal fourth quarter results could be “substantially” lower than expectations due to its decision to delay the availability of the iPhone X, one analyst told CNBC on Wednesday.

The technology giant released three new smartphones on Tuesday: The iPhone 8, iPhone 8 Plus and iPhone X. The latter is a $999 model packed full of new features. But it will begin shipping on November 3, later than the other two devices.

Daniel Gleeson, senior analyst at Ovum, said that those who would want to buy the iPhone X are likely going to be the enthusiasts who will want the latest device as soon as possible. Those who will likely buy the iPhone 8 and 8 Plus won’t necessarily be too worried about getting it quickly.

This could lead to many people waiting to see the iPhone X before purchasing an iPhone 8 or 8 Plus. Gleeson said that this could have an effect on Apple’s September quarter results.

“The iPhone X will potentially hamper and damage the sales of the iPhone 8 … that’s a very big risk because the iPhone launch events in late September have always been a very very big sales event for Apple. They’ve always helped perk up their late Q3 numbers and led into very strong Q4s,” Gleeson told CNBC in a TV interview on Wednesday.

“So what you’ll see now possibly is a Q3 that is actually down substantially on what it should have been or what it might have been expected to be, of course, with the reverse of possibly a higher Q4 on the other side.”

The iPhone will be roughly available for 8 days of the September quarter. In the first week of new iPhone sales, Apple typically sells between 10 million to 12 million units, Gleeson estimates. In the first week of the iPhone 8 and iPhone X sales, this could be cut in half, Gleeson said.

Analysts surveyed by Reuters are expecting Apple to report revenues of $51.06 billion in the fiscal fourth quarter, an 8.9 percent rise from the year before.

The promise of upgraded iPhone 8 models could also hold off purchasing, according to a note by Mizuho. Abhey Lamba, managing director of Americas research at the investment bank, said that he expects an OLED version of the iPhone 8 next year. The iPhone X has an OLED screen, which is a display technology that promises more energy efficiency and better colors. It’s the first time an iPhone has had an OLED display.

But the iPhone 8 models do not have OLED, something that could change next year.

“We expect the company to include new display technology and offer an updated design next year when OLED screens will be more broadly available. As such, mainstream iPhone users might consider pushing out their purchases to next year when they can get greater innovation at a lower price,” Lamba wrote in a note on Tuesday.

Mizuho has a “neutral” rating on Apple’s stock.

Other experts think expectations of Apple’s fiscal first quarter which runs to the end of December, could also be too high. Analysts expect Apple to post sales of $86.8 billion in that quarter, according to FactSet, up from $78.4 billion in the year-ago period. But Gene Munster, a former Apple analyst who is now a venture capitalist, said the iPhone X delay could make meeting that expectation tight.

“They failed in terms of getting that phone out in line with expectations,” Munster, managing partner at Loup Ventures told CNBC on Tuesday. “I know that that had been kind of a moving target, but that’s going to have an impact on the Street’s estimates on the December quarter, shifting some of those units from December into the March quarter.”

But some analysts think Apple was right to announce all the products, and it’s unlikely to have any long-term impact.

“Keeping it (iPhone X) quiet until a second product launch this autumn would simply alienate iPhone 8 purchasers and damage Apple’s business in the long run. Apple has made the right decision for its customers,” Ian Fogg, senior director of mobile and telecom at IHS Markit, said in a note on Tuesday.

“IHS Markit expects demand will exceed supply for these new iPhone models because they represent the biggest step forward in iPhone design since the iPhone’s debut. iPhone X will set Apple up for exceptional iPhone performance in 2018 and into the iPhone’s second decade.”