They now face France at Eden Park on Saturday for a place in the final and Jenkins in excited at what lies ahead.
"It is possibly the biggest game in Welsh rugby history," said former fly-half.
"We've been involved in a lot of Grand Slams and Triple Crowns and we got third place in 1987 but this is the biggest game I've certainly been involved in and the players have been involved.
"When Wales have won Grand Slams in the past, we're all about momentum.
"When that first win comes in Grand Slam years, we seem to get better and better.
"I know we lost to South Africa first up but it was like a psychological win for us.
"We played well on the day and thought we probably should have won the game and we took a lot of confidence from that.
"I think that was shown in the win over Samoa a week later. We've just built from there and the boys seem to be getting stronger and stronger."