These are the games than can break a title challenge. Liverpool put their advantage of playing first to good use on Saturday, winning the kind of game that can unsettle rivals in a race for silverware that shows no signs of slowing down.
For weeks Manchester City have been responding to the challenges laid down to them. First against Southampton. Then at the Etihad against Liverpool. Again against Wolves on Monday and now at Huddersfield.
On paper this was going to be as easy a three points as City would collect all season. Huddersfield were 10 points short of safety and without their talismanic manager after David Wagner's decision to walk away last week.
But the pressures of a title race can do funny things to a side. When City were seven points behind over Christmas Pep Guardiola said they couldn't afford another slip up, so with Liverpool's dramatic win on Saturday once again extending the advantage to seven - just as it had been when City kicked-off against Wolves on Monday night - this was another test of nerve for Pep Guardiola side.
If the City players had been following events on Merseyside yesterday then they would have experienced the full range of emotions. At 3.45pm Liverpool's grasp on the title looked to be slipping. But while Crystal Palace's three goals at the Etihad in December were enough for victory, their three at Anfield weren't.
Weekends like this can often be decisive in a title race. Guardiola's admiration for Maurizio Sarri's Napoli would have meant he followed their Serie A slugest with Juventus last season. Like City and Liverpool there was no quarter given, but the crucial weekend arrived when Juventus came back from the dead to beat Inter Milan on a Saturday night. Within 24 hours Napoli had folded to Fiorentina. Game over.
But Huddersfield are no Fiorentina. While City might have been dispirited at Liverpool's lucky escape on Saturday afternoon, they had enough to get three points of their own in Yorkshire.
After the events of yesterday this was a weekend City just had to survive. Now they know when Liverpool next play the gap could be down to a point if the Blues can win at Newcastle. Time to see how Jurgen Klopp's side handle the pressure.
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That the Terriers were beginning life without Wagner perhaps didn't make the occasion any easier. A farewell message from the German was due to be played on the big screen at the John Smith's Stadium before kick-off, but when Wagner appeared and began talking there was no sound to accompany the video. 'Technical difficulties', according to the PA. Huddersfield have had plenty of those on the pitch in their second Premier League season but they don't lack for fight.
They got stuck into City in the first half and Guardiola's side never really clicked into gear.
They were denied one of the clearest penalties of the season when Raheem Sterling was tripped by Terence Kongolo. It was a remarkable injustice, but the footballing gods were clearly as equally appalled at the decision as Sterling.
A couple of minutes later Danilo tried a speculative shot from 25 yards, which looked to be flying a couple of feet wide until Christopher Schindler put his head in the way, diverting the ball beyond the helpless Jonas Lossl.
Danilo's decision to celebrate with Bernardo Silva in the dugout gave Guardiola the chance to issue a few instructions to his team and he had animated discussions with Kyle Walker and Fernandinho while the rest of the side celebrated.
That Pep talk had little immediate impact though. The Blues continued to be poor in possession, with Walker booked for a needless sliding lunge on Chris Lowe. Fernandinho and Ilkay Gundogan were as guilty as anyone in failing to find the right passes and with two of their orchestra struggling to hit the right note City were finding it difficult to create chances.
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The interval initially did little to improve the Blues, but it took just a couple of minutes of classic City to take the game away from Huddersfield. First Kevin De Bruyne's slide-rule pass found Leroy Sane in the inside left position and his cross along the six-yard box was met by a diving header from Raheem Sterling.
Moments later Danilo pounced on a loose pass and immediately found Sergio Aguero, who nodded the ball into Leroy Sane's path and he finished with poise, stroking the ball beyond Lossl.
City were now in control. Guardiola could afford to withdraw Fernandinho, who had struggled, Sane and Ilkay Gundogan safe in the knowledge the game was won.
The gap at the top is back to four points. Now it's time for City to turn up the pressure.