Krzewina improved at the start of 2014 with an indoor best of 46.54 seconds to finish as runner-up at the national championships. He anchored a team of Kozłowski, Omelko and Pietrzak to take Poland to fourth place in the 4×400 m relay final at the 2014 IAAF World Indoor Championships on home turf in Sopot (Krzewina's highest global finish at that point). He opened the outdoor season with a big personal best of 45.11 seconds. This marked ranked him fourth in the European rankings for that season. He repeated that time at the Polish Championships to claim his first national outdoor title in the 400 metres. He was chosen for both the individual and relay events at the 2014 European Athletics Championships. In his solo senior debut for Poland he reached the 400 m final and finished in fourth place, just behind Israel's Donald Sanford. Having missed the heats, he was drafted in as the last man for the Polish team in the 4×400 m relay final. Starting his leg in fourth place, he narrowly overhauled Thomas Jordier in the final straight to win the bronze medals for Poland (setting a personal relay best of 2:59.85 minutes in the process). His fourth in the individual event led to his inclusion on the European relay team for the 2014 IAAF Continental Cup and (teaming up with European rivals Conrad Williams, Sanford, and Martyn Rooney) he helped the team to silver behind the African team.