The ending had some controversy, as Tsarev complained of an eye poke to referee Greg Franklin moments before Good swarmed him for the finish. Replays were inconclusive as to whether Tsarev had a case.
Whether or not the eye-poke was real, Good was in clear control to that point. The athletic welterweight neutralized Tsarev's ground game in the first period, planting him on his back against the cage and raining punches.
Tsarev responded with surprising success on his feet in the next round, but it was still the lead jab and straight punches of Good landing more. The end came at the 3:54 mark.
Good (14-2) will face Tsarev's teammate Andrey Koreshkov in the tournament final.
"That's just testimonial to how hard I've been working," Good said. "I felt comfortable even with a submission expert. I just went in there and did my thing."
Tsarev (24-3) lost for the first time since November 2008, snapping an 11-fight win streak. The 26-year-old Russian fell to 1-1 under the Bellator banner.
Koreshkov knocks out Zaromskis in the first
Andrey Koreshkov booked his way to the Bellator welterweight final with a terrific first-round knockout over Marius Zaromskis.
But the bigger story might have been referee Jerry Poe.
Koreshkov dropped Zaromskis with a hard left hook to the temple two minutes into the first round. Zaromskis fell back to the cage helpless, but referee Poe refused to stop the fight even as Koreshkov landed a series of unanswered haymakers.
The end mercifully came at the 2:14 mark of the round.
"I'm very happy I didn't disappoint anybody -- my coach, my manager, my country," Koreshkov said through a translator.
The 22-year-old Koreshkov (12-0) remained unbeaten as a professional. The Russian striker utilized his reach beautifully against the smaller Zaromskis, posting the eighth knockout of his career.
Zaromskis (19-7) saw a five-fight win streak snapped. Saturday marked the 33-year-old's fourth appearance for Bellator this year.
Straus keeps momentum going, submits Robinson
The move paid off and added to the momentum the 28-year-old had built in winning the most recent Bellator featherweight tournament.
"I want to fight whoever has got that belt," Straus said. "Whether it's 'Pitbull' (Patricio Freire) or Pat Curran, both are tough guys. I respect them both. I just want that belt."
Straus got off to a good start, taking Robinson down in the first minute of the fight. Robinson looked to counter with a guillotine, but never was close to submitting Straus, who hasn't been submitted since his first pro fight in 2006.
After failing to generate much offense from top position in the first round, Straus began capitalizing in the second frame. A series of short elbows softened up Robinson enough for Straus to work to his back and eventually lock in the finish at the 4:51 mark.
Straus (21-4) has now won five straight fights and 17 of his last 18. Robinson (12-7) lost in what may be his only fight in 2012. The UFC veteran is 3-3 since leaving the promotion in 2008.
Rogers proves too much for Steele
Rogers wobbled Steele in the first minute with a short right -- which would become a theme in the fight. The right hand was a major weapon for Rogers, who staggered the 24-year-old later in the round and had him swelling badly on the left side.
Steele did his best to rally in the third, but Rogers continued getting the better of the exchanges. All three judges scored it unanimously for Rogers, 30-27.
It was the first time Rogers has won a professional fight that extended past the first round.
"I'll tell you what, he might have Wolverine bones," Rogers said. "It was a crazy fight. Big props to Dom Steele."
Rogers (10-4) improved to 3-2 since signing with Bellator last year. Eight of his 10 wins have come via first-round knockout.
Steele, now 6-3, dropped his Bellator debut.