Photo by: HAGEN HOPKINS/GETTY IMAGES (Despite his concussion symptoms improving, Chiefs midfielder Charlie Ngatai is set for another week on the sidelines). After his year out following a head knock last season, Ngatai missed the match against the Crusaders in Fiji last Friday after reporting a headache post-training on the Monday. The team played it safe and kept him from travelling with the squad overseas the following day.Chiefs coach Dave Rennie said while Ngatai was on the improve, he was unlikely to play a part at Eden Park.”Charlie’s pretty good,” he said. “He’s had about four days symptom-free. But we’re unlikely to use him this week. We want to be really sure.”In the end we’ll take advice from the medics around that.”We just want to be really cautious around it. So we’re not going to rush him back in, but the news is pretty positive.”And there are a further two Chiefs midfielders under concussion clouds following the 31-24 loss in Suva, with Sam McNicol and Stephen Donald both failing their head injury assessments in that match.Rennie said McNicol was in a similar boat to Ngatai in that they don’t want to push things, after he missed the entire Mitre 10 Cup last year due to the same reason.”He’s had a bit of history with concussion. He actually bounced back reasonably well the day after, but we’ll tread carefully around that,” Rennie said.Donald, who is sitting on 99 Chiefs appearances, is also set to be on the sideline.”He’s actually bounced back ok,” Rennie said. “We’ll make a decision on him later, but obviously he’s going through protocols, and at this stage unlikely.”Rennie said winger Toni Pulu would probably be right to return from the hamstring injury which had him sidelined from the Crusaders game.