Thor: The Dark World is seen as one of the Marvel Cinematic Universe's weakest and most forgettable offerings, and unsurprisingly, so are its villains. Alongside Malekith, Algrim (aka Kurse) also wasn't given the recognition he deserved.
Given Kurse's extreme combat skills, unparalleled strength and immense durability, there's absolutely no doubt he could defeat Thanos in a physical confrontation — that is, of course, base-level Thanos when he's not in possession of any Infinity Stones.
Kurse's Transformation Into a Ruthless Powerhouse
Algrim was a Dark Elf who became empowered by a Kurse Stone — a mystical object used by prominent Dark Elf soldiers to improve their physical capabilities beyond other members of their species. Algrim was stabbed in the gut with one by Malekith, embedding the stone within him. Not only did he endure this brutal stabbing, but it seemingly made him more physically powerful than any Kurse Stone user who came before him.
The physical feats displayed by Kurse in the MCU were beyond anything Thanos showed in straight-up physical combat. Kurse was able to swat away Mjolnir when Thor called for it, and practically ignored the effects of its strikes. By contrast, the enchanted hammer was able to floor Thanos when it was wielded by Captain America. Kurse also manhandled Thor far more effortlessly than Thanos did, and could even better withstand damage, appearing like a solid wall of unbreakable metal.
Kurse's Strength Is Off the Charts
Kurse's was able to shrug off injuries in Thor: The Dark World like no other villain had done. He was incredibly strong, as he lifted and threw a 100-ton boulder with relative ease, beyond any feat performed by baseline Thanos. To top it all off, Kurse carried black hole grenades, far more dangerous than anything Thanos wielded on a daily basis.
Ultimately, both Kurse and Thanos were defeated — Thanos was snapped out of existence, and Kurse was taken out by one of his own black hole grenades. But based on actual on-screen feats, a Kurse vs Thanos fight could end with another defeat for the Mad Titan. Thanos would have more flair and style in the confrontation, but his efforts would be met by an unfazed Kurse, who would ultimately win through sheer strength and durability. It would be one hell of a fight, though!