They are the Mutt and Jeff of college lacrosse, but when they begin their afternoon-long dual today at Johns Hopkins, no one in the expected overflow crowd of 12,000 will be laughing.

To those attending this Hopkins-Maryland confrontation, what happens between the Blue Jays' 5-foot-7 Bob Maimone and the Terrapins' 6-1 Bob Ott in their midfield faceoff battles is most serious business. The teams are so close in talent that the outcome of the 2 p.m. NCAA semifinal game could well be determined by these two talented players.

Last Saturday, Ott dominated Maimone until the squads went into overtime. Then Maimone took charge, won a series of crucial faceoffs in the second extra period and Hopkins won, 21-20.

"There is no question that really hurt us," Ott said yesterday. "But I was really dead by the time the overtime periods came. I can't remember anything about them. I had paced myself for a four-quarter game and I didn't have anything left."

Keeping Ott fresh in the heat of the Homewood playing field is one of coach Bud Beardmore's biggest worries entering the game. And it also points up a major difference in the philosophies the teams take toward faceoffs, which occur at the start of each period and after every goal.

Ott takes a regular turn with his midfield unit as well as handling most of the faceoffs. Maimone, however, does nothing but fade off. As soon as the faceoff is over, he leaves the field for a substitute.

"I hate to see the game develop into a game of specialists," said Ott. "I wouldn't want to just face off. I like to play too. No doubt it's and advantage for him to be resting while I'm playing but it's something I have to overcome."

The two also have contrasting styles and approaches to the art of facing off. Mamimone who weighs 195 pounds and [WORD ILLEGIBLE] huge forearms and wrists, relies on bulldog tenacity and strength. Ott, an angular 185-pounder, depends on experience and quickness.

While Maimone paces back and forth before each faceoff, psyching himself for the upcoming confrontation, Ott will chat casually with a referee, trying to relax.

Despite their frequency, face offs are one of the big mysteries of lacrosse. They take place in a small area in the middle of the field and because the two players are crouched low over the ball, the view from the stands is poor.

What is taking place is simple: The players have their sticks on the ground, with the nets of the sticks about an inch apart. The official places the ball between the nets (but off the ground) and then blows his whistle.

It then becomes a matter of which player can rake or scoop the ball away from the other. Maimone, who Ott says, "practically has his nose on the ball", tries to overpower his foe. Ott tries to pry the ball loose so he can dash over and pick it up.

"It's a matter of adjusting and then adjusting again," said Ott. "We may wind up facing each other 40 times in the game. So it becomes a mental duel."

In the other NCAA semifinal, at Ithaca, N.Y., Cornell, the defending national champion and winner of 27 straight games, is a top-heavy pick over Navy, which upset Pen Tuesday.