Men’s Battle for No. 1 Resurfaces This Week : Tennis: Agassi and Sampras try clay, with streaking Muster a real threat in French Open.

The rivalry for tennis’ No. 1 ranking, currently raging between emotional opposites Andre Agassi and Pete Sampras, races on unabated. The only force powerful enough to slow them down is the red clay courts at Roland Garros.

The French Open, which begins today, has its own pace and will not be dictated to. The surface alone will see to that. Two weeks of alternate rain and heat and interminably long matches on clay will subdue everyone.

Sunday’s arrival of Agassi for a practice session, for example, drew its usual throng of teen-aged spectators. The difference here is that while the fans avidly watched Agassi before the rains came, they refrained from screaming. Cool reserve is the byword, even in the presence of the world’s No. 1 player.

The Agassi-Sampras struggle for supremacy has dominated this season. Agassi has overtaken Sampras, but each week Sampras threatens to return.

This tournament has, admittedly, been a focal point of the early season. Sampras--whose serve-and-volley game is blunted on clay--planned his entire season so that he would linger in Europe and play more tournaments on the dreaded surface.

Agassi, whose patient backcourt game is well suited to clay, has wondered aloud how it is he hasn’t yet won this tournament.

Roland Garros represents an intersection of interest for Agassi and Sampras: Each needs the French Open title to complete a career Grand Slam. Each would dearly love to be the first American since Don Budge in 1938 to have won all four titles. Each has an excellent chance.

Agassi got the better of the draw. He will meet Karsten Braasch of Germany in the first round, and Sampras will meet Gilbert Schaller of Austria, who, at No. 24, is the highest-ranked player that any seeded player will meet in the first round.

Lurking in the draw is Thomas Muster of Austria, who is on a 28-match winning streak and a clay-court devotee. There is also two-time defending champion Sergi Bruguera of Spain, whose penetrating forehand may or may not be enough of a weapon against a rejuvenated Agassi.

Arantxa Sanchez Vicario is likewise here to defend her title, but countrywoman Conchita Martinez is the hottest player on the women’s tour.

Steffi Graf, who sat out six weeks because of flu, has won three times and, for the first time in memory, enters a Grand Slam event not seeded No. 1.

Mary Pierce of France, a finalist here last year, is under pressure to add this title to the Australian Open, her first Grand Slam victory.