"How good are we?" Steve Martin, captain of Georgetown's undefeated, 20th-ranked basketball team, asked rhetorically. "I really can't tell yet. There are two questions to be answered: Can somebody else step in? Can we play well on the road?"

The second question gets its first answer tonight (WTTG-TV-5, 8 p.m.) when the 4-0 Hoyas play 4-1 St. John's, a traditional rival, in Jamaica, N.Y.

"The road test," Martin continued, "is the true test of every team. After Saturday's game, we'll have a good idea of how good or how great we are."

Maryland, Navy and George Mason are home today, but only Mason, a surprising 3-1, should be tested, playing James Madison (4-2) and the Dukes' standout power forward, Steve Stielper, who is averaging 26.5 points the Cornell Invitational consolation in Ithaca, N.Y., against Rochester.

Maryland (3-2), whose star forward, Albert King, was pronounced unfit for duty (injured knee) by team physician Stanford Lavine, hosts Biscayne College (2-3) at 8 o'clock and Navy (3-1) meets Lycoming at 2 p.m. at Halsey Field House.

Elsewhere, American U. (3-3) travels to Lafayette (3-0), where Eagle Coach Gary Williams was an assistant for seven years and recruited four of the Leopards' current starters; George Washington is in the final in the First Union tournament in Charlotte, N.C., and Catholic winds up consolation play in the Cornell Invitational in Ithaca, N.Y.

At St. John's, Georgetown will be playing its third straight opponent that participated in last year's NCAA tournament. It is Georgetown's first game outside McDonough gym or Capital Centre.

The NCAA does not keep statistics on road records but Jim Van Valkenberg, NCAA director of statistics, said: "It's an axiom, a self-evident truth. I'd say not more than 10-15 percent of the Division I teams have winning records on the road.It would be nice to have that statistic."

Georgetown fell into that select group the last three seasons, although barely, at 12-11, not counting games on such neutral courts as Madison Square Garden. At home, during the same span, the Hoyas were 36-4.

So, that is why Martin and the nation's coaches consider road performance the true test of a team. Teams that have poise, such as Georgetown has shown this season, usually are the ones who come through away from home.

Depth also is usually a requisite for playing on the road.Close calls by referees that go your way at home are likely to go the other way on the road. So foul trouble can present a problem for a team like Georgetown, whose four returning starters from last year are the Hoyas' only experienced returning players. Coach John Thompson has depended on six players this season.

In their four victories Georgetown has attempted more than three times as many free throws as its opponents. The Hoyas made their last 15 points from the foul line against Indiana and their last 18 against St. Bonaventure. Georgetown is shooting 82.4 percent from the line.

Tonight, the Hoyas will be playing a team with an outstanding back court (Bernard Rencher and Reggie Carter) and a center, Wayne McKoy, who scored 31 points in Thursday night's 83-82 victory over Baylor. Rencher, however, missed that game with the flu and was sent home with a 102-degree fever. He is questionable for tonight's game. His replacement, Tom Calabrese, is an experienced guard who is sometimes used in a three-guard alignment.

George Mason, 18-37 the past two seasons, is giddy over its 3-1 start in its first season of Division I play. Today has been declared GMU Alumni Day in Fairfax and bedsheet signs were hanging around the campus yesterday.

The Patriots' big problem will be stopping Stielper, who leads his team in both scoring and rebounding and is an offensive threat either inside or outside. Keith Lewis, the Patriot who would normally guard such a strong forward, won't regain his eligibility until next week after suffering academic problems.

At Lafayette, AU will be seeking its fourth straight win and third on the road. Center Bob (Piper) Harvey has been given the okay to play after suffering a concussion last week against CU. But Williams said he is concerned about how much stamina Harvey will have and is not counting on him for lengthy duty.