There are three important things that happen in Cambridge around the middle of October each year. The leaves turn color. Midterms invariably roll around. And Harvard plays Dartmouth in football.

The last-place Crimson (0-2 Ivy, 2-2 overall) hosts first-place Dartmouth (2-0, 2-2) at 1:30 this afternoon in the Stadium, and if past confrontations mean anything, the 82nd meeting between these clubs will be a knock-down, drag-out affair.

For Harvard, the game is the first in a series of five must-win contests that will keep the Crimson in the league race. For Dartmouth, the game represents a chance to prove that the upsets over Penn and Yale were no flukes. For both squads, the game is an extension of a nasty old rivalry.

Mean

The Big Green has produced a tough defense and an erratically productive offense in its first four games.

After bopping Penn 31-21, in coach Joe Yukica's debut, the Dartmouths dropped a pair of games to Holy Cross (35-0) and B.U. (20-17) before zapping Yale at Hanover in the mud last Saturday.

Led by co-captain linebacker Joe Nastri, the Big Green held Yale's brutal ground game to three yards rushing in the second half. On offense, sophomore tailback Jeff Dufresne (31 carries, 116 yards against the Elis) has come out of nowhere to add balance to superb quarterback Buddy Teevens's passing game.

Teevens can toss the pill as well as anyone in the Ivies--he nearly played the miracle-maker in last year's 31-25 Harvard win--and he has Dave Shula (Don's son) and Jim Eden to throw to.

Crippled

Dartmouth's surprisingly talented team aside, Harvard has a series of injuries to worry about. While tight end Paul Sablock returns to action after sitting out against Cornell, at least three key players are ailing: linebacker Craig Beling (knee), cornerback Steve Potysman (shoulder) and linebacker Bob Woolway (concussion).

The Crimson seems less than awed, though. Harvard has won the Dartmouth game four years running, and the gridders expect to continue the tradition.

"They have a good team, but they don't have a great team," senior halfback Ralph Polillio said yesterday.

"We'll just have to score a lot more points than they do," Polillio added. And that's the name of that tune. RUSHING Player  Att  Yds  Avg  TD Ralph Polillio  40  175  4.4  2 Wayne Moore  16  134  8.4  1 Matt Granger  29  108  3.7  1 Larry Brown  38  105  2.8  0 Paul Connors  42  90  2.1  1 PASS RECEIVING Player  CT  Yds  Lg  TD Paul Connors  9  88  15  0 Ralph Polillio  7  134  50  2 Rich Homer  6  111  40  0 Paul Sablock  4  57  34  1 Matt Granger  4  42  18  0 Dave Kinney  3  76  42  0 John MacLeod  3  54  35  0