The two have combined for 22 first-round stoppages — 12 for Carwin and 10 for Dos Santos — in their 26 fights.
The 6-foot-2 Carwin's first 12 fights lasted a grand total of 16 minutes, 10 seconds.
The sleek 6-foot-4 Dos Santos is accurate and decisive.
So expect lot of action Saturday night when the heavyweights meet Saturday night in the main event of UFC 131 at Rogers Arena. The winner gets a shot at champion Cain Velasquez.
"Don't leave the TV," said Carwin (12-1).
"It's not going to be by decision, for sure," echoed Brazil's Dos Santos (12-1).
The two fighters are at the top of the charts for significant strikes landed per minute in the UFC. Carwin is No. 1 at 7.65, and Dos Santos is No. 3 at 7.18, according to FightMetric.
Still both have had to look in the mirror after their last fights.
Carwin essentially punched himself out in the first round against then-champion Brock Lesnar last July at UFC 116, recording an astounding 40-3 edge in significant strikes in the first 5 minutes. His exhausted body shut down in the second and Carwin was submitted at 2:19 of the second round.
Dos Santos dominated Roy Nelson last August at UFC 117 but couldn't put him away. Dos Santos ended up winning by decision, holding a 130-40 edge in significant strikes.
"Roy Nelson has a hard chin," Dos Santos said. "But I learned a lot there, too. I was too anxious to knock him out. ... The knockout is the result of good technique in the fight."
Dos Santos believes he is "way faster" and way better" as a striker than Carwin, whose boxing skills he rates as "pretty good."
The Brazilian is almost a 2-1 favourite.