Three tenors are on course to record a UK chart first by each landing albums in the top 10.
Watson has sold more than four million albums worldwide
Newcomer Vittorio Grigolo and BBC One's Just the Two of Us winner Russell Watson are set for new entries in the top 10, according to mid-week figures.
Andrea Bocelli's album Amore, out last week, could stay in the chart.
The Three Tenors - Luciano Pavarotti, Placido Domingo and Jose Carreras - have only appeared in the top 10 at the same time when they recorded together.
Watson has released The Ultimate Collection while Grigolo's album is entitled In The Hands Of Love.
HMV's Gennaro Castaldo said: "The first time we really saw the phenomenon of classical music crossing over into the mainstream in this way was through the massive popularity of the Three Tenors in the early 1990s.
"Now the likes of Andrea, Vittorio and Russell are achieving a similar effect with a new and younger audience."
Grigolo, 29, has been dubbed "Il Pavarottino" by the Italian press in recognition of his resemblance to Pavarotti.
Vittorio Grigolo joined Milan's La Scala opera house at the age of 23
He sang with the Sistine Chapel choir from the age of nine and now incorporates rock covers by acts such as Keane in his set.
Fellow Italian Bocelli, who is blind, is a multiple Classical Brit Award winner who also sang at the second wedding of Luciano Pavarotti.
Watson, another Classical Brit winner, won the celebrity TV singing show Just the Two of Us earlier this month after he was paired with actress Sian Reeves from BBC One's drama Cutting It.
Former Blur guitarist Graham Coxon is set for a top 10 entry with his sixth solo album in the chart, which was topped on Sunday by the first solo album by Pink Floyd's Dave Gilmour since 1984.