The last time he was in a serious title challenge it was against Vettel, and Vettel wasn't strong enough mentally to deal with it. But Verstappen is strong enough, I think. He's not shown any signs at all of buckling under the pressure. He's certainly a worthy opponent for Hamilton.
If Hamilton has the faster car here, then one thing that could be important is the pace of the second drivers. Bottas looks like he should be up near the front for a change, but Perez seems to be struggling a bit. That could hand Mercedes a tactical advantage if it stays like that through qualifying. Of course I don't expect Bottas to beat Verstappen in the race itself, but he might be able to assist Hamilton.
I am not even sure about Vettel, sure he is a great driver and multiple champion but when Mercedes started their domination in 2014, nobody really got too close. Even Vettel was further away than max, even if max ends up becoming second in each race and loses the title, he will be within like 10 points or so, right? That means he would be the person who got closest to Hamilton in 8 years or so. This is by far the most hardcore season Hamilton had in his entire life.
I am not one of those people who say Hamilton only won this many thanks to his car, but it is fair to say that Mercedes has always been faster than every other car, at all times, so for the first time ever, Hamilton finally has someone who gives him a challenge and that means his "most important title" is actually true. Plus he would become the person with most titles as well, added bonus for sure.