| Grego | |
| Full Name: | Gregorio Sierra Pérez |
| Birth Date: | 5 March 1993 |
| Birth Place: | Murcia, Spain |
| Height: | 1.86 m[1] |
| Position: | Centre back, defensive midfielder |
| Currentclub: | Universitatea Craiova |
| Clubnumber: | 25 |
| Youthyears1: | –2011 |
| Youthclubs1: | Murcia |
| Years1: | 2011–2012 |
| Clubs1: | Murcia B |
| Caps1: | 12 |
| Goals1: | 0 |
| Years2: | 2012–2013 |
| Clubs2: | Atlético Madrid C |
| Caps2: | 19 |
| Goals2: | 0 |
| Years3: | 2013–2014 |
| Clubs3: | Noja |
| Caps3: | 5 |
| Goals3: | 0 |
| Years4: | 2014 |
| Clubs4: | Mar Menor |
| Caps4: | 10 |
| Goals4: | 0 |
| Years5: | 2014–2015 |
| Clubs5: | Murcia B |
| Caps5: | 26 |
| Goals5: | 0 |
| Years6: | 2015–2016 |
| Clubs6: | La Hoya Lorca |
| Caps6: | 23 |
| Goals6: | 0 |
| Years7: | 2016–2017 |
| Clubs7: | Valencia B |
| Caps7: | 33 |
| Goals7: | 1 |
| Years8: | 2017–2019 |
| Clubs8: | Numancia |
| Caps8: | 7 |
| Goals8: | 0 |
| Years9: | 2019 |
| Clubs9: | UCAM Murcia |
| Caps9: | 10 |
| Goals9: | 0 |
| Years10: | 2019–2021 |
| Clubs10: | Sabadell |
| Caps10: | 60 |
| Goals10: | 1 |
| Years11: | 2021–2024 |
| Clubs11: | Burgos |
| Caps11: | 83 |
| Goals11: | 6 |
| Years12: | 2024– |
| Clubs12: | Universitatea Craiova |
| Caps12: | 3 |
| Goals12: | 0 |
| Club-Update: | 11 August 2024 |
Gregorio Sierra Pérez (born 5 March 1993), commonly known as Grego, is a Spanish footballer who plays as either a centre back or defensive midfielder for Romanian Liga I club Universitatea Craiova.
Grego was born in Murcia, and was a Real Murcia youth graduate. He made his senior debut with the reserves in 2011, in Tercera División.
In 2012 Grego moved to another reserve team, Atlético Madrid C also in the fourth tier. On 30 July of the following year he joined fellow league team SD Noja,[2] but after being rarely used he terminated his contract and signed for Mar Menor CF in January 2014.
On 10 July 2015, after another one-year spell back at Murcia's B-side, Grego first arrived in Segunda División B, after agreeing to a contract with La Hoya Lorca CF.[3] Roughly one year later, he joined fellow league side Valencia CF Mestalla.[4]
On 28 June 2017, after missing out promotion in the play-offs, Grego signed a two-year contract with Segunda División club CD Numancia.[5] He made his professional debut on 6 September, starting in a 1–0 away win against Real Oviedo, for the season's Copa del Rey.[6]
On 23 January 2019, Grego agreed to a six-month contract with UCAM Murcia CF in the third division, after terminating his contract with Numancia.[7] On 15 July, he moved to fellow league team CE Sabadell FC,[8] being a regular starter as his side achieved promotion to the second tier.
On 31 July 2020, Grego renewed with the Arquelinats for a further campaign.[9] On 6 July 2021, after the club's relegation, he joined Burgos CF also in the second division.[10]
Grego scored his first professional goal on 3 October 2021, netting the winner in a 1–0 home success over CD Mirandés. On 3 July 2024, Burgos announced his departure as his contract had already expired.[11]
On 3 July 2024, Grego moved abroad for the first time in his career, after agreeing to a one-year contract with Romanian side CS Universitatea Craiova.[12]