Star Wars (1977) #20 and Star Wars Weekly #40

In Star Wars #19, Chewbacca is forced into The Wheel's Big Game after he hides the body of the rebel who died in Star Wars #18.  He enters a casino on the upper level where a guard confronts him for not paying a registration fee for being aboard the gambling establishment.  Chewbacca is knock unconscious by Wheel Security, but not before battling with a Mandallian Giant, an enormous muscular humanoid.  In the same issue, Han Solo gambles away his last credits trying to come up with the docking fees for the Millennium Falcon and decides to enter the contest as a gladiator to raise funds.  In Star Wars #20, Han faces off against a Ultaarian Greenback in a preliminary bout where Han Solo is outclassed by another muscular humanoid, this one with four arms each holding poisonous dagger thorns.

Star Wars #20a - Marvel Comics, U.S. (February 1979)
Newsstand

Star Wars #20's cover has Han lying on the ground while the Ultaarian Greenback approaches.  C-3PO, R2-D2, and other Wheel patrons are watching the fight while C-3PO's dialogue reveals his usual pessimism.

Star Wars Weekly #40a - Marvel Comics, England (November 8, 1978)
last half of Star Wars #20

The cover for Star Wars Weekly #40 has a similar scene with Han again on his back while his prey closes in for the killing blow.  This cover only shows C-3PO and R2-D2 viewing the battle.  C-3PO is quiet, but clearly concerned.

Both covers have mistakes with the alien Han is fighting.  On the U.S. cover, the alien's head looks more like the Mandallian Giant Chewbacca fought, except for the addition of a trunk-like nose.  The tusks are turned down, unlike the Ultaarian Greenback inside the issue, and the alien has ears which a Greenback does not have.  The color scheme does match however.  The U.K. cover shows the alien with a more accurate head, but the color more closely resembles the color for the alien Chewbacca fought.  Additionally, the alien on the cover sports spiked wrist bands that neither alien wears.  When it comes to the colors used on the British Weekly magazines, some leeway should be given since the interior pages are in black and white.  A Brit reading the comic would have no way of knowing if the color is correct or not.

Of the two covers, I like the more menace stance of the Ultaarian Greenback on Star Wars Weekly #40, although I prefer the details provided by Carmine Infantino on Star Wars #20.