Can I file a mechanics lien on a house that has just sold because the seller did not pay me in full before it sold?

A client kept promising to pay me but the house was on the market for sale. It looks like its sold but he still has not paid me. Says as soon as it funds he will. If he does not end up paying me do I have to file a lien on the property for the new owners to put pressure on the seller? I really hate to do that.