His father, who was born in Poland and was initially a tailor, was religiously observant, and had strong opposition to his son Solly's youthful desire to pursue boxing as a career.

[3] On October 16, 1931, Krieger was knocked out for the first time in his career by future 1933 Middleweight Champion Vince Dundee in Madison Square Garden in eight of ten rounds.

Describing how he could appear to be taking a beating in a fight like the one with Rankins, while actually avoiding or blocking most of the blows coming his way, he once said, "I started walking in on my opponents but I countered.

In 1938, Krieger won five straight knockouts, starting with George Black, and Al Diamond in one round, Johnny Rossi in four, and then Stanley Hasrato in seven.

In his knockout against Izzy Jannazzo, on April 6, 1938, at the Hippodrome, Krieger effectively used strong body blows to win the fight, but did not gain the eleventh-round TKO until his "wild punches" began to land.

Krieger's loss to a boxer who had no advantage in reach did not bode well for his upcoming fight with the more skilled and slightly taller Freddie Steele.

[7] Krieger had a setback against ranked opponent and reigning NBA World Middleweight Title holder Freddie Steele, on June 14, 1938, in a ten-round loss by unanimous decision in Seattle, Washington.

Continuing to fight in California, he came back with impressive wins against Swede Bergland, Ace of Spades, and Dale Spar, gaining the positive press he needed to push a title match.

Nonetheless, on November 1, 1938, at Civic Stadium in Seattle, Washington, Krieger won the National Boxing Association World Middleweight Championship in a 15-round majority decision over the reigning champion.

It wrote, "Krieger, a rough, tough, infighter at his best against hard punchers, took the offensive almost from the start, and from the sixth round it was apparent the Seattle Slav (Hostak) was in for a busy evening.

[9][10][11] After his win over Hostak, Krieger's coach Hymie Caplan made an understandable decision to forgo any challenger a title shot for a six-month period.

He still fought regularly after he captured the title from Hostak, facing Billy Conn twice in tough losses, as well as Carmen Bath, Red Farmer, Marty Simmons, Ben Brown, and Alan Matthews.

In the Matthews bout on April 5, 1939, Krieger effectively used infighting, with close body blows and hooks to defeat an opponent who was less a threat than Hostak or Steele.

[4][13] In his final fight with Billy Conn on May 12, 1939, Krieger lost again in twelve rounds by unanimous decision in front of a sizable audience in Madison Square Garden.

Though outweighing Krieger by only four pounds in the bout, Conn was significantly nine years younger and five inches taller, giving him an important advantage in reach, and probably in endurance as well.

As evidence of Conn's superior strength and conditioning, he would take the Light Heavyweight Title on July 13, 1939, only two months after his bout with Krieger.

The Milwaukee Journal wrote that in the fourth round, "Krieger, his eyes glazed and staring, slumped to the canvas in midring and sat there in a stupor for several seconds before his handlers trundled him to his corner."

After the defeat, Krieger attributed his loss to the difficult task he had losing twenty pounds in a month to make weight, and the terrific right hand of Hostak.

He fought thirteen fights in the heavyweight division gaining victories in 1940 against Texas Joe Dundee, Mario Liani, Herbi Katz, Jarl Johnson, and Wally Sears.