Question: Who is the maternal grandfather of Frederick Of Saxony (Teutonic Knight)?

Knowledge 1: Frederick of Saxony (Teutonic Knight)
Duke Frederick of Saxony (26 October 1473 – 14 December 1510), also known as Friedrich von Sachsen or Friedrich von Wettin, was the 36th Grand Master of the Teutonic Knights, serving from 1498–1510.He was the third (and youngest surviving) son of Albert, Duke of Saxony, and Sidonie of Poděbrady, daughter of George of Podebrady.The Teutonic Knights had been in a long power struggle with Poland over Prussia.Because the Teutonic Knights' fortunes had declined throughout the 15th century, they hoped that by selecting someone connected by marriage to the ruling Jagiellon dynasty of Poland, they would strengthen their position.Born prematurely seven months after his immediate elder sibling in Torgau, Frederick was a member of the Albertine line, the junior branch of the prestigious House of Wettin which ruled Saxony.Frederick should not be confused with his cousin of the same name from the Ernestine line, who ruled the Electorate of Saxony.Frederick's older brother George had married Barbara, a sister of King John I Albert of Poland.The young duke was elected Grand Master in 1498.When the Polish king summoned Frederick to do homage for the Order's holdings, he referred the matter to the Imperial Reichstag set to meet in Worms in 1495.The Reichstag informed JohnI Albert that he could not interfere in the Grand Master's free exercise of power in Prussia.Frederick's delaying tactics were assisted by the quick succession of three Polish kings during his 12 years in office.Frederick died in Rochlitz.By custom, grand masters of the Order did not marry, so he had neither wife nor descendants. [SEP] Knowledge 2: Sidonie of Poděbrady
Sidonie of Poděbrady (11 November 1449 – 1 February 1510) was a duchess consort of Saxony.She was a daughter of George of Poděbrady, King of Bohemia, and his first wife Kunigunde of Sternberg.She was the twin sister of Catherine of Poděbrady, wife of Matthias Corvinus of Hungary.
Knowledge 1: Frederick of Saxony (Teutonic Knight)
Duke Frederick of Saxony (26 October 1473 – 14 December 1510), also known as Friedrich von Sachsen or Friedrich von Wettin, was the 36th Grand Master of the Teutonic Knights, serving from 1498–1510.He was the third (and youngest surviving) son of Albert, Duke of Saxony, and Sidonie of Poděbrady, daughter of George of Podebrady.The Teutonic Knights had been in a long power struggle with Poland over Prussia.Because the Teutonic Knights' fortunes had declined throughout the 15th century, they hoped that by selecting someone connected by marriage to the ruling Jagiellon dynasty of Poland, they would strengthen their position.Born prematurely seven months after his immediate elder sibling in Torgau, Frederick was a member of the Albertine line, the junior branch of the prestigious House of Wettin which ruled Saxony.Frederick should not be confused with his cousin of the same name from the Ernestine line, who ruled the Electorate of Saxony.Frederick's older brother George had married Barbara, a sister of King John I Albert of Poland.The young duke was elected Grand Master in 1498.When the Polish king summoned Frederick to do homage for the Order's holdings, he referred the matter to the Imperial Reichstag set to meet in Worms in 1495.The Reichstag informed JohnI Albert that he could not interfere in the Grand Master's free exercise of power in Prussia.Frederick's delaying tactics were assisted by the quick succession of three Polish kings during his 12 years in office.Frederick died in Rochlitz.By custom, grand masters of the Order did not marry, so he had neither wife nor descendants. [SEP] Knowledge 2: Princess Mathilde of Saxony (born 1863)
Princess Mathilde of Saxony, Duchess of Saxony (19 March 1863 – 27 March 1933) was the third child and third-eldest daughter of George of Saxony and his wife, Maria Anna of Portugal.She was an elder sister of the Kingdom of Saxony's last king, Frederick Augustus III of Saxony.
Knowledge 1: Frederick of Saxony (Teutonic Knight)
Duke Frederick of Saxony (26 October 1473 – 14 December 1510), also known as Friedrich von Sachsen or Friedrich von Wettin, was the 36th Grand Master of the Teutonic Knights, serving from 1498–1510.He was the third (and youngest surviving) son of Albert, Duke of Saxony, and Sidonie of Poděbrady, daughter of George of Podebrady.The Teutonic Knights had been in a long power struggle with Poland over Prussia.Because the Teutonic Knights' fortunes had declined throughout the 15th century, they hoped that by selecting someone connected by marriage to the ruling Jagiellon dynasty of Poland, they would strengthen their position.Born prematurely seven months after his immediate elder sibling in Torgau, Frederick was a member of the Albertine line, the junior branch of the prestigious House of Wettin which ruled Saxony.Frederick should not be confused with his cousin of the same name from the Ernestine line, who ruled the Electorate of Saxony.Frederick's older brother George had married Barbara, a sister of King John I Albert of Poland.The young duke was elected Grand Master in 1498.When the Polish king summoned Frederick to do homage for the Order's holdings, he referred the matter to the Imperial Reichstag set to meet in Worms in 1495.The Reichstag informed JohnI Albert that he could not interfere in the Grand Master's free exercise of power in Prussia.Frederick's delaying tactics were assisted by the quick succession of three Polish kings during his 12 years in office.Frederick died in Rochlitz.By custom, grand masters of the Order did not marry, so he had neither wife nor descendants. [SEP] Knowledge 2: Princess Amalie of Saxony
Amalie Marie Friederike Auguste (10 August 1794 – 18 September 1870), Princess of Saxony, full nameMaria Amalia Friederike Augusta KarolinaLudovica JosephaAloysia Anna Nepomucena Philippina Vincentia Franziska de Paula Franziska de Chantal, was a German composer writing under the pen name "A. Serena", and a dramatist under the name "Amalie Heiter".She was the daughter of Prince Maximilian of Saxony and Princess Carolina of Parma.She was the granddaughter of Frederick Christian, Elector of Saxony; niece of Frederick Augustus I, King of Saxony and Anthony, King of Saxony; sister of Frederick Augustus II, King of Saxony and John, King of Saxony; and aunt of Albert, King of Saxony and George, King of Saxony.

Answer: George of Poděbrady