Yes, the odds for live in-play betting are updated in real-time to reflect the current state of the game. For example, if Nottingham Forest were underdogs against Brentford before the match but score to take a 1-0 lead, their odds will most likely chance to be the favourite of the match, even though they were underdogs prior to the start. This makes in-play valuable, because the odds fluctuate as the game progresses.