Not long after Soviet troops marched into Czechoslovakia in 1968, the two countries faced off in the 1969 world ice hockey championships, and there literally was blood on the ice.

On several occasions, the Soviets have met Hungary in Olympic water polo tournaments since the Budapest rebellion was crushed by Warsaw Pact troops in 1956, and, likewise, those teams left blood in the pool.

Few observers here expect blood on the field Sunday, when Poland's World Cup soccer team takes on the Soviet Union in Barcelona to determine which of the two Eastern Bloc teams will reach the semifinal to play Brazil or Italy. (France and Northern Ireland meet in Madrid; the French and Poles each can advance on a tie; their opponents must win.)

For one thing, neither team, particularly the Soviet Union, is particularly physical. Nevertheless, there is little doubt that more is at stake from a sporting point of view. Furthermore, there is every bit as much at stake in terms of national pride for the Poles, who since Dec. 13 have lived under martial law and suppression of the burgeoning movement toward overall liberalization and independent trade unions. True, there were no Soviet troops in the tanks rolling through the streets, but few Poles doubt whose pressure caused the crackdown on the Solidarity trade union movement.

Sunday's game is so big that the Poles, who have run a relatively wide-open training camp compared with the Soviets' iron-curtained practice sessions, are playing down the political angle. For public consumption, at least, Coach Antoni Piechniczek and his players say they couldn't care less about politics.

"I really just want to beat the Russians so that we have a chance to make the finals," Poland's star Zbigniew Boniek told a Western reporter here. "I'd also really like to win the goal-scoring crown."

Ryszard Skarzynski, a Polish journalist who emphasized that he was not a mouthpiece for the Communist government, said the players have been telling him the same thing.

"I ask the same question, and I've talked to all of them--Boniek, (Grzegorz) Lato, all of them--and they all say there's no political context," Skarzynski said. "You have to remember that Polish sportsmen are in a special situation, and if they had to react to every political situation in our country, where so much is happening, they could never concentrate on sports."

Present in Barcelona to back their team is a small but vocal group of Poles--about 500, or twice the number of carefully selected Soviet citizens in Spain for the tournament. But Polish emigres from neighboring France and some from as far away as the United States have added to that number. A hot item selling on the streets of Barcelona is a T-shirt with the well-known "Solidarnosc" inscription.

The Poles can count on majority support of the neutral fans, much as happened whenever the Czechoslovaks played the U.S.S.R. in ice hockey in the late 1960s.

For one thing, the Poles have turned the crowds on during the last two games with exhilarating offensive performances, scoring eight goals and earning repeated applause with their wide-open, hustling style.

The Soviets, on the other hand, have been disappointing after coming here as dark horses to win. Although they gave the big favorites from Brazil plenty of competition in their first game, the aggregation of Ukrainians, Georgians and Russians has tended to caution since, playing just well enough to get by.

After the Soviets beat Belgium Thursday night, 1-0, while taking but one serious shot on goal, the Barcelona crowd showered the winners with jeers and whistles. Many Brazilians and Spaniards started chanting "Po-lo-nia" (Poland).