He was speaking on Thursday night's Off The Ball
Chelsea stretched their winning league run to 11 games last weekend with a narrow 1-0 win over Crystal Palace at Selhurst Park.
The Blues have looked in imperious form, conceding only two goals over the course of those 11 games and getting the most out of their 3-4-3 formation.
Speaking on Thursday's Off The Ball, John Giles backed Chelsea to go on and win the league, but highlighted one potential downfall in Antonio Conte's side.
"I think the only problem they have is that the squad is a bit thin," Giles said. "If anything happened to Costa, they could be in trouble.
"He has this window coming up, so I wouldn't be surprised if he bought a couple of defenders and a forward. I think he will have the means to do that. I don't think they'll stop him spending the money.
"A good thing for them is that they're not in Europe so they haven't got those fixtures. But there's always a possibility that somebody could get injured in training. I think that's the only thing that could stop them."
Antonio Conte has enjoyed life in the Premier League since taking charge at Chelsea this season. Image: Matt Dunham AP/Press Association Images
He also explained the impact of being out of additional competitions this season; no Champions League means that Chelsea are able to avoid midweek fixtures to focus fully on the Premier League.
"It's no coincidence that the teams not involved in the Champions League, the Europa League and the various cups have a better chance of winning the league. It's just down to the fact that there's less fixtures.
"Going back to my time, we were in the race for the title most seasons. We won it two years and the two years that we won it, we were out of the cup competitions."