Jimmy Connors, whose bad foot in January eased John MeEnroe's path to the Grand Prix Masters title in Madison Square Garden (7-5, 3-0, default, in the semis), is ailing again - much to the irritation of McEnroe.

As the World Championship of Tennis' eight-man finals commence in Dallas, McEnroe will take the court tonight against John Alexander for a match originally scheduled for Wednesday. Connors was supposed to play Gene Mayer in the opening session but sent a doctor's excuse from Las Vegas: infected left hand. WCT's Mike Davies, nothing there had to be a match tonight because tickets had been printed and sold, thrust McEnroe-Alexander into the breach.

"I'm not happy about it," McEnroe declared. "I came here prepared to play Wednesday. Why can't both matches be played Wednesday? They can play Connors Sunday at midnight for all I care but I still want to play Wednesday."

If Connors is to play Sunday, it will be in the afternoon (happy TV), and he will have his work (starting Wednesday) cut out for him. His doctor says he has not only finger wound (from a broken callus) but respiratory problems and a swollen toe, but "I'm sure he will play. He is very determined."

So, presumably, are Bjorn Borg and Geoff Masters, Vitas Gerulaitis and Brain Gottfried, Thursday's first-round pairings. Semifinals Friday advance two toward Sunday's battle for $100,000 first prize.

James Madison U. has honored Steve Blackmon, 6-4 soph forward from Eastern (D.C.) High, as defensive MVP on its 18-8 basketball team . . . The pro soccer writers say Tommy O'Hara of the Dips is NASL defensive player of the week for taming Tulsa's Roughnecks . . . And, dee-fense, dee-fense, can Bobby Dandridge do it all? The NBA coaches have elected the Bullet offensive star to their all-defensive five, along with Philly's Bobby Jones at forward; Kareem Abdul-Jabbar of L.A. at center; Phoenix's Don Buse and Seattle's Dennis Johnson - 20 of 22 votes for top rank - at guards . . .

In springfield, Mass, the 12th annual National Basketball Hall of Fame inductions yesterday brought this from inductee Wilt Chamberlain: "Looking back on it, I'm glad I came from Philadelphia. It was the mecca of basketball back then."

In Boston, the Celtics are ready to induct as their coach, if he's amenable, Dave Cowens' old college coach, Hugh Durham (then of Florida State, now of Georgia). Red Auerbach interviewed Durham here on the weekend, after Indiana U.'s Bobby Knight passed.

Bird Fidrych, by not going to Evansville, eludes trying to throw strikes to baseball's littlest one, 5-3 shortstop Harry Chappas whom the White Sox quietly demoted from starting status to Iowa of the American Association the other day . . . That left K.C.'s Fred Patek uncontested as the bigs' littlest, but is he long for the Royals? "He's killing us out there," Manager Whitey Herzog has been saying as 5-4 Freddie keeps committing throwing errors. "We're going to have to do something. Freddie's been a heck of a player when he could play, but my coaches don't think he can play now." G. M. Joe Burke still thinks he can, though.