Chelsea welcomed former Blues boss Antonio Conte back to Stamford Bridge for the first time as a league opponent, and got the better of Tottenham once more after their Carabao Cup success.
The teams went in goalless at the break, after Harry Kane thought he had put the visitors ahead only for his goal to be chalked off for a push on Thiago Silva.
Chelsea came out stronger in the second period, with Hakim Ziyech's stunner putting the home side in front and Silva adding a quickfire second when he headed home a free-kick.
Both sides had further chances in the closing stages, with Hugo Lloris and Kepa Arrizabalaga called into action, but Thomas Tuchel's side hung on to widen the gap to their London rivals and make their position in the top four a little more comfortable.
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1. Conte's back four gamble almost pays off
If you were asked to identify one characteristic of Antonio Conte's time at Chelsea, you would point to the back three system he introduced just a few weeks into the season.
A 3-0 September 2016 defeat at Arsenal accelerated the switch, with the Blues responding by winning 13 on the spin as wing-backs Victor Moses and Marcos Alonso helped Conte's side race to the title.
It's a formation we had already seen from the Italian during his time in international football, and his Spurs team had operated with three central defenders... until Sunday's game.
Tottenham started with Japhet Tanganga at right-back and Ben Davies on the left, attempting to suffocate Chelsea by also using Matt Doherty and Ryan Sessegnon in front of the defence.
While the set-up wasn't necessarily to blame for either goal, Tanganga had a tough afternoon and was withdrawn before the hour mark - along with the ineffective Sessegnon.
Whether or not Conte persists with the approach going forward, squad depth - rather than systems - could be the issue.
2. Ziye ch delivers again in fruitful run
Things haven't entirely clicked for Hakim Ziyech at Chelsea, but his goal against Brighton in midweek was enough to earn him a third successive Premier League start for only the second time this season.
He went as close as anyone in the first period, drawing a save from Hugo Lloris with a speculative left-footed shot, but he made no mistake at the start of the second period.
Ziyech's curler from the edge of the area was the exact kind of magic Chelsea fans hoped to see when he signed from Ajax, and no goalkeeper in the land would have stood a chance.
The Moroccan's international exile worked in the Blues' favour against the Seagulls, and so it proved again.
3. Kane incident reignites VAR debate
After the penalty drama at Selhurst Park in the day's early game, there was another contentious decision which arguably changed the course of the game at Stamford Bridge.
Harry Kane thought he had given Tottenham a first-half lead after spinning and turning the ball beyond Kepa Arrizabalaga, only for referee Paul Tierney to rule it out for a push by Kane on Thiago Silva.
Co-commentator Gary Neville insisted it wasn't a foul, though those in the studio disagreed with the former Manchester United defender.
The incident once again raises the question of real-time incidents versus slowed-down replays, though sticking with an initial decision - a foul was called in real time - is different from making a revision based on a replay.
It could have been a very different game is Spurs had gone in at the break with a lead to defend, and there is no doubt the debate will rage on.
4. A tale of two goalkeepers
The game was Chelsea's last in the league without Edouard Mendy, or at least they'll hope that's the case, with the Senegal keeper's Africa Cup of Nations involvement ending on FA Cup fourth round weekend.
While the Blues have dropped points without their number one, stand-in Kepa wasn't tested all that much by a Spurs side who had failed to beat him in two cup meetings, with a late Kane header producing the toughest save he had to make.
At the other end, Spurs showed the value of an experienced head between the sticks, with Hugo Lloris keeping his side in the game after recently signing a contract extension.
The World Cup winner had little chance with the opener, but produced a big save to deny Ziyech a second just moments later and left his line to make two big interceptions at 2-0.
At least there's one position where Conte is unlikely to need January reinforcements.
5. Bergwijn's chance after Leicester drama
There was inevitably going to be clamour for Bergwijn to start after his dramatic cameo against Leicester City, but the Dutchman's role in west London was a little different.
He was a willing runner in the first period, getting close to Kane where possible, but didn't get a real sight of goal until his team was already 2-0 down.
With talk of a move for Adama Traore continuing, it was a chance for Bergwijn to show he can also make a difference against top-four opposition where opportunities are often scarcer.
Still, while that didn't happen, the omission of Dele Alli from the matchday squad suggests that - if Bergwijn is up for sale - he's certainly not the first name on the discard pile.
6. Lukaku showing improvement but still no goal
After drawing a blank in both legs of the Carabao Cup semi-final, Romelu Lukaku was hoping to make it third time lucky.
His movement was certainly better than in the recent league defeat against Manchester City, but he missed two presentable chances in the first half when a sharper striker might have scored.
The Belgian had another opportunity after the break, and it was one he created for himself, shaking off his man before testing Lloris from the left-hand side of the box.
Lukaku has been told the only way to ease the pressure will be to start scoring again, and that advice is probably right, but his all-around game was much better.
Perhaps, with his former mentor Conte watching on, he decided he had a point to prove beyond the obvious. However, that wait for a league goal goes on.
