Small delay defects are important to detect after manufacturing and during in-field testing. Small delay defects are detected by tests for path delay faults. Path selection criteria consider the length of a path, the ability to detect a path delay fault, and the need to cover every line in the circuit. The similarity to a functionally possible path (one that can be activated during functional operation) was also considered as a criterion for the selection of path delay faults. Functional considerations in the selection of path delay faults are important for ensuring the detection of small delay defects that can affect the correct functional operation of the circuit. Especially during in-field testing it is important if defects that can affect the correct functional operation of the circuit are detected since such defects can be responsible for silent data corruption that has been reported recently. This article suggests a path selection criterion and test generation procedure that focus on small delay defects that can affect the correct functional operation of the circuit. Experimental results for benchmark circuits demonstrate the need for this criterion.