The Boston Bruins will be without their top two centres when they open their preseason in China later this week.

Bruins general manager Don Sweeney announced Monday David Krejci will not fly out with the team on Tuesday due to a visa issue. The team had already announced No. 1 centre Patrice Bergeron would not make the trip due to injury.

The Bruins will open their preseason Saturday morning in Shenzen, China against the Calgary Flames. They will face the Flames again on Sept. 19 in Beijing in the second of their two overseas contests.

The Bruins will be without several of their top players on the trip. In addition to Krejci and Bergeron, captain Zdeno Chara, defenceman Torey Krug and forwards Noel Acciari and Anders Bjork were all ruled out last week.

Bergeron is still not 100 per cent after off-season groin surgery. Captain Zdeno Chara, who is 41, isn't going to avoid wear and tear, Krug is coming off a broken ankle, Acciari had sports hernia surgery and Bjork had shoulder surgery.

The Bruins are taking four centres who are looking to make the leap to the NHL this season on the trip in Jack Studnicka, Jakob Forsbacka Karlsson, Trent Frederic, and Colby Cave. Sweeney said the trip should allow each centre plenty of looks in front of the coaches.

“Bruce (Cassidy) and the rest of the coaching staff, we are all excited to see how they integrate into the main group and see who has a chance to carry the ball,” Sweeney said.