First, Sandberg played for the Swedish club Åtvidabergs FF. He won with Atvidabergs 1970 and 1971 Cup and 1972 the championship. He has 17 goals scorer in 1971 and was able to repeat in 1972, but now together with his teammate Ralf Edström, each with 16 goals. In Europe Cup Winners' Cup, he turned with his club in the 2nd round from Chelsea. In the return match, he scored in the 66th minute the decisive goal to 1:1 draw. To round in 1973/74, the striker moved to the 1 FC Kaiserslautern in the Bundesliga. Right at the third use him his first Bundesliga goal succeeded in the match against Eintracht Frankfurt. He completed his debut in Round 32 league games and scoring on the side of Striker Klaus Toppmöller (21 goals) 19 goals. The "Red Devils " occupied the 6th place. For four years he played with the " Red Devils" and scored 62 goals in 117 games. His biggest success in Kaiserslautern was reaching the final of the DFB - Pokal 1975/76, which lost the Palatinate 0-2 against Hamburger SV.
In 1969, he debuted in the Swedish national team for which he played a total of 37 games and scored 15 goals. With the successful World Cup qualifying in 1972 and 1973, he was active for his country against Malta, Hungary and Austria. In the playoff on November 27, 1973 against the same number of points Austria team, he scored in a 2-1 success in the 12th minute the 1-0 lead. With the Football World Cup 1974 in Germany, he played six games and scored two goals. First, he prevailed with his team-mates in the group and moved to the 2nd place in the final round. He made it with Striker Ralf Edström the spearhead. In the game on June 30 in Dusseldorf against Germany, he scored in the 53th minute the goal for interim compensation 2:2.