Oxford midfielder Mark Sykes has received his first call-up to Northern Ireland's senior squad for the upcoming Euro 2020 qualifiers.

Sykes, 21, and Hearts defender Michael Smith have been added to Michael O'Neill's squad for the games in Estonia a week on Saturday and Belarus the following Tuesday.

Smith returns after injury but Sheffield United midfielder Oliver Norwood is still absent following his decision to withdraw temporarily from international football.

Sykes has been in impressive form for Sky Bet League One side Oxford since joining them from Glenavon in January.

Hearts defender Aaron Hughes, Northern Ireland's most-capped outfield player with 112 caps, has been included in the squad.

The former Newcastle centre-half is expected to retire as a player this summer and did not feature in Hearts' Scottish Cup final defeat to Celtic last weekend.

O'Neill's squad head to Austria on Monday in preparation for next Saturday's match against Estonia in Tallinn.

Northern Ireland currently sit top of Group C, three points ahead of Germany, who have a game in hand, and Holland after winning both of their opening matches against Estonia and Belarus in Belfast in March.