Chalk up another great week for 16-year-old Tiffany, who continues to dominate charts in the U.S. and Britain with the first two singles of her short but spectacular career.

And the Californian continues to reign on the American pop list with "Could've Been," which had no trouble holding the No. 1 title because its two closest challengers-the Bangles' "Hazy Shade of Winter" and INXS' "Need You Tonight"-fell right out of the Top 5.

But next week, look for "Could've Been" to again dominate the all- important pop list, although this week's No. 2 song, "Seasons Change" by the Miami dance group Expose, still has a slim shot at the title. Out of contention is this week's No. 3 single, Roger's "I Want to Be Your Man," which has already started dropping in radio airplay.