First, it was an assist for Diego Costa to break the deadlock against West Bromwich Albion at the weekend, and then Cesc Fabregas followed it up with the winning goal at Sunderland on Wednesday.

Chelsea are six points clear at the top of the Premier League, and the Spaniard can claim to be a big part of that. Indeed, remove him from the equation and that lead may well be a lot more slender if we factor in his role in the Blues winning their last two matches.

Continuing their winning run as they have has been vital to Antonio Conte's side asserting themselves as the Premier League's runaway leaders heading into the Christmas period.

On Sunday, the Blues capitalised on Manchester City and Liverpool dropping points. Three days later, they did the same after Arsenal's defeat to Everton by winning their 10th game in a row to take a maximum 30 points from 30 available.

And at the heart of it all recently has been the man we were beginning to forget about. Fabregas' impact over the past three games—he was inspirational in Costa's equaliser against City, too, setting up Chelsea's 3-1 win—has been incredible.

The Spaniard has picked up two assists and a goal to keep Chelsea pulling away from the teams that trail them. He has been a renaissance man of epic proportions; Fabregas is back to the sort of levels we saw from him in 2014/15 when his link-up play proved such a vital factor in winning the title.

Back then, the Blues ran away with their crown, not giving anyone a chance to even threaten them. They were top from the opening weekend right through to the last. It took them a bit longer to get up and running this season, but it's no coincidence that Fabregas has played a big role at the crucial moments. He hasn't played anywhere near enough for his own liking, yet here he is, dominating the conversation.

That Fabregas' goal in the 1-0 win at the Stadium of Light on Wednesday came on the anniversary of Jose Mourinho's last game as Blues manager made it feel all the more significant.

It was on December 14, 2015, that Mourinho's side went down 2-1 to Leicester City. Chelsea were in crisis; they were Premier League champions, but the defeat left them languishing near the foot of the table. It was the time when—as we started to look for the reasons for why—we started to lose faith in Fabregas' brilliance.

Now look at him. This time last year, faith was disappearing, but now he's restoring it. The perspective has changed since he started at the Etihad Stadium in Nemanja Matic's absence on Dec. 3.

"I'm pleased for him because he always showed a great attitude and behaviour," Conte told BBC Radio 5 live Sport at the final whistle of Chelsea's victory over bottom side Sunderland. "[...] It's important that when I call on my players I have a great reply."

It's the last part of Conte's comment that is most important here. Fabregas is a professional footballer, and he should maintain a good attitude and behaviour to his work. That's a prerequisite, but that alone isn't what wins league titles and other silverware.

What claims silverware is the sort of cutting edge Fabregas is showing us he still has. He isn't being carried by the rest of this squad, but he is playing a vital part in Chelsea's resurgence as England's leading club. That's crucial and must have Conte licking his lips.

The manager has played the biggest role at Stamford Bridge this season. It hasn't just been a formation change, it's also a different perspective that has got his team more recognisable to what we should expect from them. Chelsea are no longer pushovers, they have more substance about them now.

Fabregas is putting himself in that category. He joked in his post-match interview with the BBC about the perception that he can't defend, flipping the notion by suggesting he doesn't have to when he is getting further forward and scoring goals that are winning Chelsea football matches.

He laughed his way through those statements, yet we shouldn't be fooled into thinking that he wasn't making a point at the same time. It was almost as though Fabregas was reminding us that his defensive duties are one thing, but what he does in the final third can be much more beneficial for this Chelsea side.

Costa knows all about that. It took just two minutes for Fabregas' introduction against West Brom on Sunday for him to benefit from having his Spain team-mate on the pitch, as it was Fabregas' pass that eventually led to his goal.

To call it an assist is probably stretching it. It was an assist by default, as Costa still had so much to do before unleashing his shot beyond Ben Foster and into the top corner.

The point is, though, that Fabregas' pass was different to anything else we had seen all afternoon at Stamford Bridge. He didn't need multiple touches before assessing his options—he knew what he was doing immediately.

That instant action turned the Baggies' defence for the first time in the game, and—in the form we find him—that one opportunity is all Costa needs right now. It was game over for West Brom.

That's what Fabregas does for any side he is playing in. He gets the ball forward quickly and with purpose, which is exactly what Chelsea have needed in their past three matches. They were trailing City and needed to get back into the game soon after the interval; they did so because of Fabregas.

Against West Brom and Sunderland, the challenge was different. Against a six-man defence on each occasion, Chelsea had to turn players and get them out of position. That doesn't come easy, especially when the ball is being moved laboriously through midfield.

It's the Fabregas effect that prevented those matches from being the banana skins they appeared on paper. It's Fabregas who has added the panache to Chelsea's lead at the top of the table.

Fabregas is no longer the forgotten man; he's vital to Chelsea.

Garry Hayes is Bleacher Report's lead Chelsea correspondent. Follow him on Twitter @garryhayes