Scarlets wing North left the field after 28 minutes in the 27-19 defeat at the Suncorp Stadium with a dead leg.
His club mate Williams was also led off the field after coming off decidedly worse in a huge collision with Australian hooker Tatafu Polota-Nau.
"George suffered a dead leg that he just couldn't run it off. He will be assessed by the medical team, but he'll be fine," said Howley, who was part of the Lions' coaching staff on the 2009 tour of South Africa.
"Scott Williams took a nasty bump to the lip, but he is OK. They should both be available for next weekend."
Also in the frame for next week's vital game with the Lions' next opponents will be Ospreys lock Ian Evans.
The man who played every single minute of the five games in the Grand Slam campaign earlier in the year arrived in Australia in the early hours of Sunday morning having flown in a week late after getting married in Greece.
"Ian could be on the bench on Tuesday night when we play the Brumbies. He will also come into contention for selection in the second Test," added Howley.
"Tuesday is an opportunity for the other guys to get a game against the Brumbies. Some of the players will have to back up from the Test, but that's the nature of things when you come to the southern hemisphere to play two games in a week.
"It will be a great learning experience for a number of the younger players. Let's not forget how young this side still is, yet they have shown a lot for maturity this year."
The game in Canberra on Tuesday night will allow Howley to take a look at the rest of his young squad, although he will be more than mindful of the strength of the home team.
Both Howley and fellow coach Neil Jenkins played the last time Wales met the Brumbies in 1996. Howley scored two tries, Joe Roff got four and the home side won 59-25.