While it's a bit early in the week to exactly forecast just how big either will be, industry sources are suggesting each should sell well over 400,000 downloads by the end of the tracking week on Sunday, Aug. 18. A start of over 500,000 for each wouldn't be out of the question either.
The final sales tally for both will be released on the morning of Wednesday, Aug. 21.
If both tunes sell over 400,000, it would be the first time two songs have debuted in the same week with more than 400,000.
Further, it would mark the first non-holiday week in over a year where two songs sold over 400,000. It last happened on the May 5, 2012-dated Digital Songs chart, when Maroon 5's "Payphone" debuted at No. 1 (493,000), pushing Gotye's "Somebody That I Used to Know" down one slot to No. 2 (463,000).
Perry's "Roar" has a slight head start in the sales race, as her song had a 24-hour jump on "Applause." So, the former will get a full seven days worth of sales in its first week, versus "Applause's" six days.
Both songs preview new studio albums for each superstar. Perry's "Roar" leads her "Prism" set, due out Oct. 22. "Applause" is the first single from Gaga's "ArtPop," which arrives on Nov. 11.
Gaga's last studio album, 2011's "Born This Way," was led by its title track, which debuted with 448,000 downloads after only three days on sale, according to Nielsen SoundScan. (It hit retail on an off-cycle Friday, instead of the usual Tuesday.) In its second chart week (and first full sales week), it moved 509,000 downloads.
Perry's last new album, 2010's "Teenage Dream," was ushered in by "California Gurls." It bowed at No. 1 on the Digital Songs chart with 294,000. Perry has sold more than 400,000 in two previous weeks: when "Firework" shifted 509,000 over the busy post-Christmas week of 2010, and when "Part of Me" debuted in 2012 (411,000).
'ROAR'-ING TOWARD HOT 100 'APPLAUSE'?
How are the songs' Billboard Hot 100 fortunes shaping up?
As previously reported, "Roar" is likely headed for a debut in the bottom half of the Hot 100 on the chart to be released on Billboard.com this week, highlights of which will post on Wednesday (14). The start will stem only from its airplay through Tuesday (13); its expected lofty sales (and streaming) figure will not factor into its chart rank until the chart released the following week, when a hefty sales sum could translate to a vault into the top five.
"Applause," meanwhile, is likely not to reach this week's Hot 100, unless its airplay today and tomorrow is enough to spur a debut in the chart's lower rungs. Like "Roar," its sales and first full week of airplay and streaming will make it a force on next week's Hot 100, with gigantic sales also potentially leading to a top five entrance.
Thus, as Perry and Gaga battle in the iTunes Store this week, we'll know who ranks higher on next week's Hot 100 after each song has had a full week of music buyers, streams and radio programmers weighing in.