Now that Georgetown has completed most of its tuning up, it's time for the Hoyas to get down to serious, meaningful basketball.

Young and highly rated (ninth in the latest United Press International poll, 13th in the Associated Press rankings), the Hoyas will get their greatest test so far this season against St. John's in their Big East Conference opener tonight at Madison Square Garden.

Georgetown (11-2) has won 10 in a row, but those opponents aren't in the same class as St. John's (9-1), winner of the recent Holiday Festival and ranked 18th by UPI and 20th by AP.

It also will be the Hoyas' first game in a charged-up atmosphere such as the one they will encounter in the Garden. The Hoyas may have been able just to dip their toes into the hot water and get by the past month, but they are jumping in with both feet now.

Eight of Georgetown's victories in the winning streak came at home. The other two came in the Rochester Classic last week, when it beat Columbia and Niagara.

Columbia held the ball against Georgetown and the Hoyas won, 38-26. St. John's beat Columbia, 58-51, Saturday.

The Redmen have a six-game winning streak. In winning the Holiday Festival last week at the Garden, they beat Kansas, 76-75, in the first round and Villanova, 94-89, in the championship game.

Tonight's game is the second game of a doubleheader. Wichita State (9-2), another final four candidate, plays Iona in the first game at 7. That game will not be televised in this area. The Shockers are ranked ninth by AP and 12th by UPI.

Georgetown Coach John Thompson took his team to New York early yesterday and practiced in the afternoon. Forward Mike Hancock, who sat out Saturday's easy victory over Robert Morris with a sprained ankle, practiced and probably will start against St. John's. If he doesn't, freshman Anthony Jones, the starter against Robert Morris, will take his place again.

The Hoyas and Redmen play similar games--press and run. The Redmen lack an intimidator like Georgetown's Patrick Ewing (3.5 blocked shots a game), but they have a lot of talent.

Their leading scorer and rebounder is 6-foot-6 junior forward David Russell, who is averaging 20.2 points and eight rebounds. Their next-best player is freshman Chris Mullin, a 6-6 guard from Brooklyn (15.7 points).

Russell was the Big East player of the week last week and Mullin was the rookie of the week.

St. John's only loss was at Rutgers, 74-67, in early December.

"We're getting better," said St. John's Coach Lou Carnesecca. "Georgetown is one of the top teams in the country. It's only one game, but it does mean a lot to both teams.

"Ewing is everything he's supposed to be and (Eric) Floyd is a proven all-American."

Ewing, a 7-foot freshman center, is averaging 14.1 points and shooting 70 percent from the field. Floyd, a senior guard, is averaging 16 points and shooting 52 percent.

As a team, Georgetown is shooting 52 percent and limiting its opponents to 39 percent.

In other games tonight, Elizabeth City is at the University of the District of Columbia, 8; George Mason tries to break a four-game losing streak at South Carolina, 8; Montgomery-Rockville plays at Montgomery-Takoma Park, 4; Montgomery-Germantown is at Howard CC, 7:30, and Anne Arundel plays at Prince George's at 1.

In women's games, George Washington is at Pittsburgh, 7, and Harford at Prince George's, 3.