Perceptual invariance has been studied and found in several domains of cognition, including those of speech, motor behavior, and object motion. It has also been the topic of several studies in music perception. However, the existing perceptual studies present rather inconclusive evidence with regard to the perceptual invariance of expressive timing under tempo transformation in music performance. The current study used a novel experimental methodology that took advantage of new technologies, such as an online Internet setup, high-quality audio, and state-of-the-art tempo-transformation techniques. The results show that listeners could detect which was the original performance when asked to compare 2 recordings, 1 of which was tempo-transformed to make both similar in overall tempo. This result is taken as support for the tempo-specific timing hypothesis--which predicts that a tempo-transformed performance will sound less natural than an original performance--and as counter-evidence for the relationally invariant timing hypothesis, which predicts that a tempo-transformed performance will sound equally natural.