Mr. WordyThis doesn't seem quite right. The subject of this instance of "is" is "Lewis Hamilton", not "expectation".
First, I should apologize, as Mr. Wordy is exactly right. Not sure how/why I made a boneheaded mistake confusing the subjects. Mea culpa. Thank you for correcting that glaring error, Mr. Wordy.
Optilang makes a good point as to reasons for choosing singular over plural. Without knowing the exact situation, both do work, as others have stated.
However, in my mind, I'm leaning towards the plural as more preferable (but not more correct) because I'm biased by the the phrase "causing him immense problems."
If the problems are "immense (and multiple ones at that)", I would sort of expect him to be hammered by multiple expectations, not just a single one. I suppose if the single expectation was very strong, it could lead to a lot of severe problems, but I still favor the plural.
New2Grammar Avangi, I've been paying attention to why he is sometimes used without knowing the gender. Is this common? Or Do you know Anon?
By the way, I agree with your interpretation of what the questioner wanted. However, I don't see why the plural is more effective. Any explanation you can offer? Thanks in advance
See my thoughts above on the plural issue. As for the question of 'he' when the gender is unknown, it is indeed very common. In English, if the gender isn't specifically known, it's generally assumed to be male.
There is of course a lot of talk about this being sexist language, and some movements towards using non-gender specific pronouns, but there's of course debate over political correctness vs. tradition, blah blah blah. You may see things like 'he/she', 'they', or even the odd 's/he' being used in an attempt to avert sexist language, but it's still the norm to just use 'he' unless it's known that the subject is feminine, at least for the time being.