The defending champion Crusaders could be without the services of All Black scrumhalf Andy Ellis when they face the Bulls in a Super 14 crunch match in Christchurch on Friday.

Ellis, who injured his ribs in the Crusaders' 11-7 win over the Stormers at the weekend, is in doubt for Friday's encounter with a Bulls team still smarting from their 12-36 loss to the Highlanders at the weekend.

Veteran fullback Leon MacDonald, who suffered a broken nose, should be available for Bulls match.

Openside flank George Whitelock, who missed the win over the Stormers due to a cut thigh from Waratahs the previous week, should be available for Bulls match.

Adam Whitelock's first try in the Super 14 helped the Crusaders to a hard-fought victory over the Stormers.

Whitelock scored after 32 minutes, finishing a move on the right wing thanks to a great wide pass from the fullback, MacDonald.

It means the Crusaders have won two in a row, following their narrow win over the Waratahs in Sydney the previous week. Before that the Crusaders drew with the Western Force, snapping a three-match losing streak.

Skipper Kieran Read said after the Stormers win that it was "tough at times" out there.

"Things didn't really go our way, but we just had to guts it out," Read said.

"We didn't hold on to the ball as well as we should have. We turned it over too often and perhaps didn't support the ball carrier enough."