Chiefs winger Lelia Masaga has been called into cover for Wulf, and a decision on the North Harbour winger's availability will be made today.
Wulf's injury occurred when he and Hesketh both jumped for the ball from a Stephen Donald kick-off at training yesterday morning.
Neither let go of the ball and both landed heavily on the ground.
Hesketh, who has been training with the All Blacks all week to make up numbers, got up straight away but Wulf was slow to his feet, clutching his left shoulder.
He was immediately seen by medical staff and quickly left the training field at the University Oval.
His arm was put in a sling and he took no further part in a lengthy training.
All Black doctor Deb Robinson said yesterday afternoon, in a statement, Wulf was in some pain and was to have an X-ray on his shoulder last night.
A decision would be made on his availability today but Masaga was rushed to Dunedin yesterday as cover.
Wulf was due to start his fifth test tomorrow night.
Masaga was training with the Junior All Blacks in Auckland yesterday.
They were about to leave for their first game in the Pacific Nations Cup in Samoa.
All Black captain Mils Muliaina said Wulf's injury was very tough on him, as he had been training hard and was excited to be playing in the test.
He said Masaga would be excited about coming into the All Blacks squad, and had the advantage of knowing the Chiefs players in the squad.
If Wulf does not play, he will probably be replaced by Wellington fullback Cory Jane, who has been with the team the whole week, and was originally named in the squad.
Masaga, who has yet to play a test, will not be able to train with the team, apart from a light captain's run at Carisbrook this morning.
He had been in outstanding form for the Chiefs early in the season, before being slowed by an ankle injury for more than a month, and he returned to the Chiefs only in the final stages of the Super 14.
The All Blacks will have their captain's run at Carisbrook this morning, while the French will have a run at the ground this afternoon.
The French have been based at Auckland for about two weeks, and arrived in Dunedin yesterday.
An All Black capping ceremony will take place at Carisbrook tonight.
The New Zealand Rugby Union had originally handed out caps to test players on their debuts but that practice ceased at the end of World War 2 and did not start again until 1997.
The union decided last year to award caps to those who missed out, and other ceremonies would take place throughout the country as the season goes on.
The union will hand out caps for 27 players tonight, though seven of the caps will go to the players' families, as they have died.
Players such as Doug Bruce, Laurie Mains and John Timu will be given caps.
The union is also holding the annual reunion for former All Blacks, referees and officials at Carisbrook tonight.
Seventeen of the newly capped players will form a guard of honour for the test tomorrow night.
Highlanders halfback Sean Romans is on stand-by to join the Junior All Blacks in Samoa.
Romans (23), may join the side as replacement for Hurricanes halfback Alby Mathewson, who has a shoulder injury.
The New Zealand Rugby Union is seeking approval from the IRB to include Romans in the side.
The Junior All Blacks play Samoa in Apia on Sunday, in the first game of the Pacific Nations Cup.
