Twitter Counter, which tracks and analyses Twitter usage, said on Thursday that, according to its algorithms, the Biebs will overtake the Mother Monster around 16:23 on Sunday.
"For now, Lady Gaga is in the lead in follows alone," it said in an email to subscribers. "Bieber's account, however, is growing at a faster rate."
Lady Gaga, who has led the Twitter pack since August 2010 when she outpaced fellow pop star Britney Spears, had 33 159 886 followers - and Bieber 33 102 814 - shortly before 16:00 on Thursday.
Both are currently on tour in the United States.
