Just because the opposition have opened the bidding it doesn’t mean you can’t bid. In fact, with the right hand, it’s good to enter the auction. You might get to play the hand, you can take up some of the oppositions’ bidding space and you can suggest a lead to partner.
Unlike an opening bid, points don’t matter so much. A good 5-card suit is the key. A good rule of thumb is two of the top four honours in the suit. Also, you indicate a good lead to partner because you promise a good suit.
If your partner overcalls, you shouldn’t get too excited about bidding. Remember, an overcall shows a good suit, not a good hand.
Unless you have a good fit with partner, you are better to pass. Don’t change suit, just because you don’t have a fit. Partner might not have one with you either and you could get too high.
But, if you do have a fit, it’s good to support partner. 3-card support will be enough, because partner is showing a 5-card suit.
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