ObjectivesTo examine (i) whether levels of, and changes in, athletes’ basic psychological need satisfaction (BPNS) and challenge appraisals predicted in-match thriving; and (ii) if salivary biomarkers could be defined that were related to thriving. DesignProspective study design. MethodsFifty-one elite male hockey players (Mage=24.94 years, SDage=4.73) completed questionnaires measuring their BPNS and challenge appraisals on seven consecutive days prior to a competitive match, as well as providing saliva samples immediately on waking, and then +0.5, +3, and +5.25h on the day of the match. Saliva was assayed for catabolic (i.e., cortisol) and anabolic (i.e., dehydroepiandrosterone [DHEA]) hormones. In-match thriving was assessed retrospectively using measures of subjective performance and well-being. ResultsLatent growth curve modelling showed pre-match levels of BPNS and challenge appraisals to positively predict thriving. Although not statistically significant, small and moderate negative associations were found for thriving with cortisol concentration (+5.25h sample) and total cortisol exposure across the morning of the match, respectively. DHEA concentration shared a small positive, yet non-significant, association with thriving. ConclusionsAthletes’ pre-match levels of BPNS and challenge appraisal predict in-match thriving; thus, offering potential mechanisms through which both high-level performance and the experience of well-being can be facilitated. Furthermore, associations suggest that total cortisol exposure across the morning of the match, and cortisol and DHEA levels in pre-match samples may offer sport science and sports medicine practitioners potential biomarkers for thriving. Future research is required to substantiate this initial finding.