It's natural that tennis coach Jack Barnaby is worrying about today's match against Yale at New Haven. Successful coaches invariably are habitual worriers, and Barnaby has an Eastern title and as undefeated season riding on this match.

Maybe Barnaby remembers last season, when Harvard downed Princeton, Yale, and everybody else until Penn upset the Crimson, 5-4, in the final match.

Like the Penn team of last year, Yale is not quite as strong as Princeton or Harvard. But with the home court advantage, it only takes a couple of flukes to reverse a match -- and a season.

Yale's got the top player in New England at number one, a stocky fellow named Jack Waltz who serves and volleys as though he were a foot taller than his 5-9. He'll be playing Crimson captain Dave Benjamin, who lost to Waltz, 6-4, 4-6, 6-4 in the semi-finals of the New England intercollegiates last spring.

Harvard should be able to win close matches at numbers two and three. Bernie Adelsberg will face Eli pretty boy Mike Brooks, a nice stroker with without Adelsberg's power.

At number three, Crimson senior Clive Kileff faces old rival Jay Westcott, whom the undefeated Kileff has edged a couple of times in the past.

The scary thing about Yale is that the team is strong this year down low. Against Princeton, the Elis won all three of the bottom single matches.

Nevertheless, it's hard to believe that anyone is going to ruin steady Richie Friedman's undefeated season. He'll meet Bob McCallum, the former number one freshman who defeated Adelsberg last season.

Jose Gonzalez, at five should edge Yale's Bill Keeton if he continues his superb play of the past few weeks. In the sixth match, Crimson junior Dick Appleby plays Bob Haar, who won an impressive victory over Princeton's Clinch Belzer last Saturday. Appleby, though, can play some of Harvard's best tennis when he's on his game, and the match should be rated a toss up.

Where Harvard should outshine the Elis is in the doubles. Appleby and Brian Davis will have lots of problems with Yale's first doubles team of Brooks and Waltz, but the other Crimson teams of Adelsberg-Gonzalez and Benjamin-Kileff ought to win.