Clive Owen has the most impact among the four stars, probably because he has the role that is technically the hero, i.e., the man capable of effective action. This isn't heroic romance, however, and so you remain aware of what goes into Larry's maneuvering—not just the good intentions, intelligence, and judiciousness, but the male rage, class resentment, deviousness, and competitiveness. In his first, vain triumph after he's been told he's a cuckold, Larry provokes Anna into telling him the dirtiest truths about her affair and then says, "Thank you for your honesty. Now fuck off and die … you fucked-up slag." (The scene is so superbly orchestrated that you credit Larry with the combined skills of Marber, Nichols, and Owen. You wouldn't want to hide a secret from him.) Owen doesn't hold back any more than Roberts does, but he does so without losing what makes him magnetic onscreen.
Owen originated the role of Dan in London, so the change in roles protects him against seeming overpracticed in his role. More to his credit, you never think of Owen's considerable vocal flair as "theatrical," anyway. It's how a man like Larry dominates a room, a situation. He's Clark Gable the sexual realist with more temperament than Gable had as an actor (Gable always overrelied on simplified gestures, such as the trademark smirk) and without the airbrushing of Gable's character imposed by MGM.
The fact that his face isn't perfect, and Larry admits it, only helps. Larry's emotions seem to be legible in the cells of Owen's mug, allowing him to get the most effect from utterly direct readings. Owen suggests Larry's awareness that he may not win, and in the strip club we see the negative side of his stability and strength—the sadomasochistic flagrance of the civilized caveman's misery. Owen's great feat is to embody his crafty archetype so thoroughly that he crosses the natural/artificial narrative boundary. As Larry, he's Harlequin armed with a truncheon, and his performance provides the heat and energy that fuse Marber's amazing composite structure.