I reckon this is precisely the type of awkward spot that separates the long-term consistent winners from the rest (placing myself firmly with 'the rest')
Against an unknown player it's a difficult lay down given the pot odds/potential outs - we've invested £120 already, so £500 more to win a total £1240 pot means we should call if we think we have 40%+ odds to win. We have 13 pure outs (9 diamonds + 4 10's) / approx 52% chance of winning if we assume our opponent doesn't have a set or a diamond(s).
However, assessing strong likely opponent holdings & and our chances of winning, we are:
- 33% against any set 9-9/K-K/4-4
- 43% against K-9
- 40% against K-4
- 32% against a random
xd
- 28%, worst possible shape, against
-10d
This to me is such a marginal spot - it's a close fold if we believe we're up against a player who is rarely/never bluffing. Our best 'strong' opponent hand is K-9, which is less likely against our tight opponent. However, it gets more complicated if we add in a bluff % (maybe 10-15% in this spot?) for our opponent, particularly given we haven't a made hand as yet!
In conclusion, if I'm in this spot against a player I believe capable of bluffing here I make a sigh call. An opponent who never bluffs = fold. This is a good illustration of why to take a few minutes to think over our opponent's possible holdings in such a spot, as I'd imagine most people call off here quickly....