the first-ever AFL–NFL World Championship Game. Chiefs owner Lamar Hunt had founded the AFL, while Green Bay was widely considered one of the best teams in NFL history (even if they could not claim to be founding members of their league, as the Packers joined the NFL in 1921, a year after the league's formation). Lombardi was under intense pressure from the entire NFL to make sure the Packers not only won the game but preferably won big to demonstrate the superiority of the NFL. CBS announcer Frank Gifford, who interviewed Lombardi before the game, said Lombardi was so nervous, "he held onto my arm and he was shaking like a leaf. It was incredible." The Chiefs saw this game as an opportunity to show they were good enough to play against any NFL team. One player who was looking forward to competing in this game was Len Dawson, who had spent three years as a backup in the NFL before joining the Chiefs. However, the Chiefs were also nervous. Linebacker E. J. Holub said, "the Chiefs were scared to death. Guys in the tunnel were throwing up." In the week before the game, Chiefs cornerback Fred "The Hammer" Williamson garnered considerable publicity by boasting he would use his "hammer" – forearm blows to the head – to destroy the Packers' receivers, stating, "Two hammers to (Boyd) Dowler, one to (Carroll) Dale should be enough." The Packers practiced at UC Santa Barbara, and the Chiefs at Veterans Field in Long Beach. The two teams played with their respective footballs from each league; the Chiefs' offense used the AFL ball, the slightly narrower and longer J5V by Spalding, and the Packers played with the NFL ball, "The Duke" by Wilson. The AFL's two-point conversion rule was not in force; the NFL added the two-point conversion in and it was first used in the Super Bowl (XXIX) that season, in January 1995. This is also the only Super Bowl to feature the offset double-support goalposts and where the numeric yard markers were five yards apart, rather than ten as is customary today. The "slingshot" goalpost, with a single support, became standard in . In , marking yard lines ending in "5" were disallowed in the NFL in order to standardize field markings. Justin Peters of Slate watched all the Super Bowls over a two-month period in 2015 before Super Bowl 50. He