Left-armer Panesar, 25, said last week he did not consider himself the first-choice tweaker following off-spinner Swann's impressive performances in the 3-2 one-day series win over Sri Lanka in October.
But Moores, speaking to reporters in Colombo on Sunday, said Panesar had done enough in his short Test career to be regarded as the frontline spinner when the first Test opens in Kandy on December 1.
"Monty has proved he is an outstanding Test match bowler and has been over the last couple of years," the coach said.
"The one thing you can say about Monty is that he has grown a lot as a bowler in the last few Test matches and you would expect him to do well over here.
"Certainly he is our number one Test match spinner."
Panesar has taken 73 wickets in 20 Tests at 30.80, while his former Northamptonshire colleague Swann has still to play a Test match and has seven wickets from five one-dayers.
Swann could make his Test debut if Michael Vaughan's men decide to field two slow bowlers in the three-match series expected to be played on spin-friendly wickets that suit the home team's Muttiah Muralitharan.
But Moores will settle for Panesar at the start.
"Nothing against Graeme, because he has done well in the one-day games, but he still has stuff to do," the coach said.
"He has a great opportunity because he showed in one-day cricket what an aggressive spinner he can be and at times we might play two."
Panesar and Swann get a chance to settle down in the two three-day practice matches to be played against Sri Lankan board teams in Colombo this week.
The first match will be played from Tuesday and the second from November 25.
This will be followed by three back-to-back Tests in Kandy (Dec 1-5), Colombo (Dec 9-13) and Galle (Dec 18-22).