Sam Solomon, who trained Leon Spinks when he upset Muhammad Ali for the world heavyweight boxing championship, said yesterday Spinks was an unconditioned fighter on Sunday when he was knocked out in the first round by Gerrie Coetzee of South Africa in Monte Carlo.

Spinks was knocked down three times before referee Isidoro Rodriguez of Venezuela halted the bout with 57 seconds left in the round.

Solomon, who now lives in Washington, watched the fight on television and said, "When I saw Leon clawing and grimacing at Coetzee I knew something was wrong. None of the punches was hard enough to hurt him that much. Leon takes a punch better than that. Coetzee is a slap hitter Leon was hit harder than that when he won the light heavyweight title in 1970 Olympics and he didn't even quiver. Leon wasn't in shape; I could tell by the way he came out flailing, trying to get it over.

"He left his head up high; he had no style. His legs wouldn't let him stand. Coetzee hit him high on the head. Coetzee himself was way off balance earlier in the round and missed a right hand like an amateur, after Leon missed."

It was reported in Monte Carlo that relations between Spinks and his new trainer, Henry Grooms, had been strained and Grooms departed for the United States yesterday, before the rest of the spinks entourage.

Spinks was not available for comment immediately after the bout on Sunday, but when he left the arena he said, "I'll be back."

John Sawyer, Spinks' acting manager said yesterday that his boxer had gone against the planned strategy. "Leon had been told to keep to the left of Coetzee and box for the first two rounds before starting any attack, but Spinks did not consider any defense and fell prey to Coetzee's right.

"He was nervous before the fight," Sawyer said, "and overconfident in the ring. He perhaps underestimated the South African. He thought of frightening Coetzee with a fast start."

Sawyer added, "We have already contacted Top Rank (the promotional firm) to have Spinks fighting again by September. His next opponent could be Kallie Knoetze, possibly in South Africa."

Knoetze recently was knocked out by John Tate of the United States.

Cotezee, 221 3/4 pounds, is now unbeaten in 22 bouts. Spinks, 198 1/2, suffered his second loss in 11 bouts, the other coming when Ali regained the championship.

Solomon said "Leon (25) is still a young man. If he gets his head together and wants to do it, he casn still be the best heavyweight in the world. He and Larry Holmes (World Boxing Council champion) are the best of the crop.

"I blame Bob Arum (head of Top Rank). He instigated internal trouble before the second fight with Ali. He made bad statements in New Orleans about Leon staying out all night. Leon later accepted Arum's apologies. Now he has served his purpose for Arum.

"I was against Leon fighting a South African. They tried to get me to do it, but I refused because of South Africa's racial policy. The first thing I knew, I was out (as trainer)."

Arum was reported as saying the Tate-Coetzee bout will be held in South Africa if the Boxing Board of Control there mandates integrated seating. CAPTION: Picture, Leon Spinks, left, "wasn't in shape" for bout he lost to Gerrie Coetzee, says his former trainer. UPI