By Slash Lane

Published: 12:00 PM EST

While robust Mac sales are likely to drive Apple to yet another solid quarter, it will be discussion of iPhone metrics that dominate the firm's fiscal third quarter conference call next week, according to Piper Jaffray.

"We expect Apple will be slightly ahead of Street consensus when it reports next week," analyst Gene Munster wrote in a report Monday. "Outperformance will likely be driven by Mac units and, to a lesser extent, initial iPhone sales."

Munster said iPhone revenue will not be material to the company's third quarter earnings, as the handset went on sale with only two days left in the quarter. Even if Apple managed to sell half a million units in that time, it would only account for an additional $12 million in immediately recognizable revenue due to the company's plan to defer its iPhone accounting over a 24 month period, he explained.

Still, the analyst expects the focus of the company's quarterly call to be weighted heavily towards discussion of the handset's metrics. Like it does with Macs and iPods, Apple will be breaking out iPhone sales into a distinct data category. This means it will report precisely how many iPhone units it sells each quarter, beginning with the first two days of sales at the end of its third fiscal quarter ended June 30th.

Although Munster's original model calls for Apple to have shipped about 200,000 units during the quarter's end, he believes the company may have sold as many as 500,000 iPhones during the first weekend, which would be well ahead of the Street's 330,000 consensus estimate.

"The key metrics of focus on the call will be iPhone units and iPhone inventory levels," he wrote.

In regards to Apple's other business segments, the Piper Jaffray analyst said he's looking for iPod unit sales in the 9.5 to 10.0 million range, and Macs in the 1.6+ million range.

"We expect slight upside to Mac units in the June quarter, based particularly on continued strength in portables, as Apple updated both the Macbook and Macbook Pro during the quarter," he told clients.

The analyst, who maintains an Outperform rating and $160 price target on Apple shares, also believes the company will use its July 25th conference call to once again guide conservatively for its current fourth fiscal quarter of the year.